Oh dear, no nightmares, please! It's really okay; people are so friendly here, and it's so much fun once you get the hang of it. Check out some of the communities to find people who are interested in the same things you are. Check out the LiveJournal Newbies Lounge, which will answer some of your questions and give you ideas about how to use LiveJournal's various features. Here are the Frequently Asked Questions. Don't be shy about commenting: that's how you get to know people; and everyone I know is absolutely thrilled whenever someone responds to something they have to say. If you have any questions, just drop me an e-mail anytime.

Oh, and here are the answers to the two most frequent questions that new users ask:

How do I add a link to another journal or website in my journal?

and

How do I use an lj-cut? What are the other LiveJournal-specific tags?

You'll be a pro in no time.