You are in the right place then.
LARP stands for Live Action Roleplaying. First lets start with the word roleplaying. Roleplaying is the playing of roles. The whole point of roleplaying is having a character. A character is also referred to as a PC.
The system we use is called TYR LARP, which stands for Thank You Realms LARP. Realms is another LARP system that TYR originated from. Right now TYR LARP shares some common ground with Realms (such as most of it's basic combat rules) but it has developed into a significantly different LARP system. People still refer to TYR LARP as just LARP and the two terms are interchangable.
Did you ever wish that you were this mighty warrior with a giant sword trying to avenge his parents death? Did you ever wish you could wave your arms and cast a fireball? This are called character concepts. Its basically ideas of what your character should do. For really good character concepts you need to think about their personality, their ideals, their code of honor, their little buttons, their ambitions, their weak points. Based on the ideas I mentioned then you can realize if you would be a warrior, a mage, a thief, a priest even a monk, and what type of creature you would like to be. You need to define your character so well that you can become him/her. Usually experienced roleplayers can just think of everything on the spot. Do not worry though if you end up staring at the ceiling thinking for hours. You kind of have to get use to the idea.
So now you have this amazing idea about your PC. You are this half Ogre that is slow, but he is so amazing when it comes to blacksmithing, and he always means good. He tries to protect the town from "bad guys" and listens loyally to every command that the captain of the guard says. Suddenly someone comes up to you and asks, "What's your mother's name?" or "How long did it take you to come to the town of New Byron?". You never thought about it have you? Make up something on the fly. Its part of character development. There are things we do not think of in-character creation that sometimes people ask as. If your character's personality is developed enough you can make something up that would make sense for your character.
Now the roleplaying part. This character that you have thought out carefully and developed has to become you. In roleplaying you never say "my character casts a fireball", you say "I cast a fireball". Hopefully this does not sound totally crazy. In order to pretend to be something you have to pretend you are that something. In roleplaying you get the chance of changing your role as an individual, and suddenly from this computer scientist student from Greece you become Og the half Ogre. It sounds very simple but in reality a lot of people have trouble letting go their own selves and enjoy their characters.
Hopefully now you have a very basic idea of what roleplaying is. Time to get to the Live Action part of LARP. If something is live action its basically happening right now. That concept is taken a step further in roleplaying. Instead of you saying "I cast a fireball", you have a fireball and you really throw it to someone with the use of a fireball prop. It just ends up being lots of fun because not only you get to become your character and talk to people but now you have the ability to really have a sword fight, or to really run away scared by a big troll comming after you.
Now we come to the concept of events and practices. A practise deals with the fighting aspect of LARP. During a practise you get the chanee to learn how to use a sword and other weapons of your choice and you get introduced to the basic fighting and safety rules. It is important to realize that during a practise there is no PCing, that is reserved for events.
During an event you get the chance to interact with other PCs that have their own separate personalities, inner politics and goals that might go along with yours or totally go against your ideals. Like "real life" you can make friends, enemies, trust people, and get hurt by people. This sounds pretty interesting but imagine being in an event for five hours and all you do is talk to other PCs. There is people that enjoy that, I am one of them. However if you are this die hard warrior you wouldn't likely just sit there and talk in the inn all the time. All events include a number of NPCs. NPC stands for Non Player Character. In other words its not a PC, but its a person doing what he/she was instructed to do by the event holder. There are good NPC that will help you, like the friendly hermit that will give you food when you are hungry and tell you about this amazing armor he can make you if you bring him some magical components. There are also "bad" NPCs that want to kill you and steal your money. Sometimes with certain character concepts what most people consider someone a bad NPC you might see him as a good NPC. For example the town gets attacked by a horde of zombies commanded by a powerfull necromancer. Most people would try to kill the necromancer so that they can defend themeselves. However if you are a necromancer that is trying to learn the higher arts of necromancy then he is the kind of guy that you want to talk to and become friends with.
Another thing that I would like to point out is the difference between in character and out-of-character. During an event you should almost always be in-character. It basically means that you are roleplaying your character, and everything that is said from you, is actually said by your character. However sometimes you might have to go out-of-character for various reasons, for example asking a marshal a rules question. Obviously its not your character doing that, its the "real" you, the out of character you. Out-of-character is commonly abbreviated as OOC, and in-character as IC.
To check out when practices and events take place check out the schedule.
As you probably realize by now there are always multiple combats that you might get yourself in. Which means that you might die from a sword hit or magic or even poison. Most of the times a helpful priest might resurrect you. However sometimes you might get permanently killed. It does not happen often but it does happen. PCD stands for Player Character Death. It basically means that you were killed and this character will never come back. You hopefully had fun playing him/her so now its time to create a new character concept and repeat the cycle.
In the LARP system there are people that are called marshals. They out of character are in charge of people's safety and following of rules. They should be respected when they make a call because if they are doing it they have a reason. If you find yourself not agreeing with a certain call for example a marshal says you got hit on the arm when you did not. Do not raise your voice and yell, you can just talk to them and explain what happened from your point of view. Marshals are human beings so they make mistakes but that does not mean that people should not listen to them. All marshals are experienced players and have helped in the development of the rules of the TYR LARP system so they know more than anyone what is right and what is not.
Some things to keep in mind that people tend to not realize but are extremely important.
All warmed up? Now go and create your character here.