What does it mean when I see a "hold" on my account?
The hold is very likely related only to registration. Your program advisor generally takes care of your registration after you tell them which class you want to register for.
How do I get my class paid for?
This is something that you'll need to contact your supervisor about to see if you qualify for employer tuition assistance.
How do I know which textbook that I'll need to purchase for my class?
You can take a look at the Classes page.