Find a qualified instructor, choose proper equipment, learn emergency procedures like minor sail repair. Once you have taken basic instruction and a class on the equipment you can then procede to a better board.
One of the more difficult steps in learning windsurfing is uphauling the sail. It requires some strength and ability to balance on the board while pulling up the sail. Remember that the elements are constantly changing -- water and wind -- do not stay static. When uphauling, use more of your weight instead of pure arm strength to counterbalance the sail.
It all comes down to knowing how to swim. Can you swim? Can you swim deep into an ocean? Have you had some experience surfing before or even skateboarding? this is an extreme sport so there are many risks involved. If you are willing to take the risk, then you are ready to go.