At 6' tall and nearly 200 lbs. the best boards for learning to windsurf are probably the Starboard Start
Large and the Rio Large.
These are high volume boards with lots of width to make them stable.
They have EVA decks to make them "beginner friendly".
You would need a light weight rig in the 4.0-6.0 meter range to get started.
The wind conditions where you intend to learn will have alot to do with what size rig is the best for you as an absolute beginner.
As the other poster suggested, try to find a windsurfing school or take a vacation at a windsurfing resort and get good insttuction on the basics for a qaulifed and certiifed windsurfing school.
Once you have the basic skills learned at the school, the choice of boards that will work best for you
is far greater, and you may have advanced your skills enough to get onto a < 180 liter short board.
Then you would not need the super wide beginner/ trainer board and could choose a board based on the wind conditions where you will be sailing most often.
Hope this helps,