Thanks Irulan...Yes, I understand the basic mountain biking skills, like moving around on the bike, leaning forward, getting off the back of the seat, etc.
I am fearful.. of falling.
My fitness level is not so good. After two years of riding it seems to have actually worsened instead of improved. I get out of breath quickly going uphill and have very little upper body strength. I am told that if I just keep riding it will get better.
I don't know about newbies or girls groups - I have only ridden with my boyfriend. As it is, I haven't even been taught how to put my bike on my roof rack.

I am in the Denver, CO area.
My boyfriend, being the expert that he is (he also works in a shop) really thinks he is a good teacher. Everything he tells me is in agreement with what I read.