Hi! Welcome aboard!
Well, it won the Origin award for being the best ruleset of its year, so perhaps its you?
I'm perfectly willing to help you, but you should be aware that many of the line's authors post here. David, the guy who wrote the book, in your estimation, very badly, is one of the moderators. You should consider your tone, is all I'm saying. Keep it friendly.
The experience rules work like this:
Time is measured in seasons. There are 4 per year. They are actual, natural seasons. Each season, pick if you are going to do labwork, or not. If you aren't a magus, then "not" is your automatic choice, OK?
If you are doing labwork, go to page 94, which is the first page of the lab chapter. This chapter lists all the things you can do in a lab. Choose one. The section will either crossref you somewhere else or give complete rules in section, OK? After you are done, you go to the next step anyway.
If you are -not- doing labwork, then go to page 163. This is where you spend experience points.
You get XP from the following sources:
Exposure: just living your life gives you a trickle of experience. This is why even if you do magic in this season, you need to nip past here, to pick up you Exposure XP. If you have done both magic and exposure, then that's you done for the season, amigo.
Adventure: You get a straight point bonus for finishing stories.
Deliberately learning in your free time: In Ars you get more XP for -not- adventuring. That is, you get XP for sitting around, and the goal of any sensible adventurer is to go home and enjoy your life. You do this in one, and only one per season, of four ways:
Practice a skill you already know, on your own (page 164)
Train under a master (page 164)
Be taught by a teacher (page 164)
Read a book (page 164-165).
If you can clarify which bit is catching you up, we might be able to help more: this question's a bit nebulous.