Writing my first novel

I read that to begin, tell everyone you are a writer. So here goes. "I'm a writer"
I have begun by creating my characters. That is so much fun. It's like playing God. I can create them, how they look, where they live what will happen to them, even how they'll die if I choose that for them. It's very invigorating to play a deity.
I already know I want this to be upbeat, humorous and a quick read. I'm not sure how the bad guys are going to pull off their bad guy deeds, but I'm formulating an idea. It takes place in SW Florida, because no one ever takes SW Florida seriously so that will be new. All the main characters will be baby boomers with all the accompanying histories, issues, grown kids, aging parents, divorce and dating again. They'll have the aches and pains of getting older, but they're still very much in the game. They just will not be nearly as glamorous as the usual 30 somethings, but not Murder She Wrote either. They'll still be looking for money, sex, pot, a place to live or a new career, just in their own baby boomer ways.
The advice I've read is "just do it". Don't worry if you think it sucks, you can always rewrite it or start a new one, but you'll at least have the experience of having done it once. So, sucky or not, here I go.