Hi, newangela, and welcome!
If you were baptized when you entered the Church, all your sins, including Original Sin and all your personal sins were washed away, and you are starting fresh from that day. No general confession is needed.
If you had been baptized before and you were confirmed and received your first Communion without Baptism (which can only be received once in your life), you do need to make a general confession that goes back over your entire life.
The website in the first reply is very good. If you want an examination of conscience with more detailed questions, either let us know and we’ll get one for you, or Google “examination of conscience,” and you’ll find all kinds of good ones.
The informal nature of the sacrament is meant to make things easier for you, not to stress you out. A lot of new Catholics think there’s some kind of formula you must use in order for confession to “work.” In truth, although there’s a standard outline that we follow, the only thing that absolutely must be said correctly is the absolution, given by the priest.
The thing you must keep in mind is to confess all of your mortal sins (once you figure out what they are! :)). Leaving any of them out on purpose because of shame or whatever reason will invalidate your entire confession. Be assured that the priest will not think any less of you because of what you confess, no matter what it is. The bigger the sin, the more he will admire your courage, and the happier he will be to relieve you of the burden. Also, the priest is strictly forbidden, under penalty of excommunication, to ever disclose your sins to anyone, so whatever you say is perfectly safe.
After mortal sins, choose a couple of venial sins that give you particular trouble and which you are very motivated to get rid of. Some people confess every venial sin they can think of week after week, without any real effort to stop committing them. That’s a waste of time. Pick them off a couple at a time when you are truly sorry for them. That’s the way to make good progress.
Although the rule is that one must confess once a year, it is much better for your soul to go more often than that. If you’ve gone twice since Easter, you’re on a good path. For myself, I find every week to be a little too soon, and every month a little long. Two to three weeks is a good interval for me. Find out what works for you. If you struggle with a habitual mortal sin, it’s good to go often to help you overcome it and to be in a state of grace so you can receive Holy Communion at Mass. If not, you can be more flexible.
Hope this helps. Always ask questions, either from us or from your priest. This is the sacrament of peace.