Hi, gingerweasel, and welcome to WriteWords
How about starting Line 1, Page 1, Chapter 1
But seriously, it's best to just dive in. The more writiing practice you get under your belt the better you'll get. It doesn't have to be a novel; it can be a short story, a blog, an anecdote. The thing to accept, though, is the 'shitty first draft'. It's never going to be perfect on the first run though, that's why God invented editing.
All the best with the writing, and if you need any help navigating the site just give us a shout.
- NaomiM
<Added>If short stories are oyur thing then you might consider checking out the Flash Fiction Group because they have regular writing contests, and writing exercises are always a good way of getting the creative juices flowing.
<Added>Just to add, as a part member you can join one Group and upload one piece of work.
You'll find the Groups here:
http://www.writewords.org.uk/groups/