You get the title from the seller, fill it out, and take it to the DMV.
Then you hand it to them (the people at the DMV). Then you NEED to show proof of insurance to get a car registered! You can have your insurance company fax it to the branch of the DMV that you're going to if you havent had a chance for it to come in the mail yet.
THEN you pay sales tax, registration, and title transfer fees. You can fudge the amount of purchase on the title if you want, they'll never know. I always put 500 bucks for a bike. Unless it's a Ducati, no one will question. That way it's much cheaper. You can be honest if it makes you feel better, though.
And that's it. They'll send you your title with your name on it in the mail in a few weeks, they'll give you a plate, and registration.... and you're done!
It's really a fairly painless process.
