Hi. The key to finding the right board is to get something that you can physically control without sacrificing too much stability. Depending on your characteristics (physique, height, weight, etc.), anything in the 7-9 feet range will be ideal until you get the basics down. More important than length, however, will be the width and thickness of the board, because this will contribute to stability and the ability to absorb waves longer than the length of the board. I bought windsurfing boards for myself
https://easy-surfshop.com/ take a look and you will definitely find what you are looking for.