As everyone is saying, you need to just get back to basics a bit and ride gentle green terrain that has a good even pitch and is well groomed. Really focus on proper body movements to control your your board. If you took a lesson to learn to snowboard initialy this helps as you are aware of proper movement concepts. Iy you are self taught, it may be a little more difficult as you may not fully understand the how and the why of controlling your board.
Yo will do everything the exact same way as riding in your regular stance; using the front foot to twist the board in the direction you wish to turn and complimenting this action with a slight shoulder roatation and a shifting of the hips. Just keep your turns nice and wide, even and at a constant rate to train your body to perform correctly so you can pick up speed and increase the difficulty of the terrain.
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