Here's a tutorial on how to do a solo boat launch.
Gene Jensen, aka Flukemaster, gives a concise and orderly tutorial on how to do a solo boat launch and recovery from a trailer.
Many of Jensen's video tutorials are designed to help the beginning angler learn how to fish. He also helps anglers learn many of the tangential things associated with the sport, such as this review of how to perform a smooth solo boat launch and recovery.
I recall when I was learning how to launch a boat by myself. If I had had a video lesson like this one I'm sure things would have gone a lot more smoothly.
Backing the boat down the ramp is a skill that can feel a little tricky the first time or two you do it, but Jensen offers some great, simple advice for first timers.
He also offers some excellent advice on courtesy at the boat ramp. A lot of new anglers are no doubt unfamiliar with some of the unwritten courtesy "rules" of fishing. Jensen's advice will help you avoid some possible embarrassment or ill will.
One last thing: Don't forget to put the boat plug in!