Between Angel and Dan, there's little to add. I would wager near anything that your problem is pretty much solely nerves. That is, of course, quite understandable...the first time is typically a huge first step, and this is something new to you. Nerves are pretty understandable here.

Take it slowly...don't rush into sex. Explain to your friend that you're just nervous due to the newness of it all, and take things slowly...get comfortable with cuddling/kissing, then more intimate touching, and then, finally, sex. Don't walk before you crawl.

Good luck and hugs,
Harley