Chris:

What type of plane is it? Electric or glow ?
If it is glow, please get help from an experienced pilot. It will save
you a lot of time and MONEY in the long run. I realize today it is an ego trip to proclaim that "I taught myself" but you'll enjoy the
hobby much more if you don't have to do a lot of unnecessary
rebuilding or replacing the whole plane.
Trimming out just means to get the plane to fly straight and level.

Randy