Very wierd to be posting to the Mountain Biking section. First time!

Okay, ladies, here's the deal. I've just been doing road riding. Over the weekend, my club leader gave me his old mountain bike. Just out of the blue! It is a huge blessing since I've always wanted to go. And now I can!

I have no idea if it fits correctly. It is so entirely different from the road bike (!) that I feel like a baby rider again. On a little ride down the road I was coming to a stop, tried to unclip from the pedal, and realized I had forgotten how to stop and dismount without my clipless pedals! Threw me for a loop! On the other hand, I had tons of fun riding over speed bumps. Tried to catch some air...

Anyway, back to subject. There is a ladies only mountain biking clinic this weekend. I am tossing around the idea of going, however I am uncertain about the bike. Since it is a hand-me-down, I am hesitant about showing up if the bike really doesn't fit me at all. ( )I need some general guidance about how to think about and go about doing all of this. Where do I take it from here???