Creating an ID or account on Facebook is actually pretty easy.
Just go to the site's homepage (Facebook.com) and the sign up for will be staring you in the face!
You then need to go through 4 steps to fill out your profile:
Find your friends
Fill out your info
Add profile pic
Some of these steps can be skipped for later, but Facebook will always prompt you to fill the out when you first join.
Finally, you will be sent an email to confirm your email address. Just hit confirm on that, and your profile will be ready to go!
You'll get guided through the various elements of Facebook, how to upload images, post status updates etc... But for such a complex platform, I think Facebook does a pretty good job of helping you get started.
Let me know if you have any other questions about getting started on Facebook and I'll be happy to help!