Put your shooting hands foot slightly infront of the other. I assume you know how to hold the ball (hard to descrive with no visuals). As you bring the ball up, bend your knees slightly, as your go to release the ball, unbend your knees, make sure you flick your wrist, and DO NOT, AT ALL, pull your hand back down before the ball reaches the rim / net.
Reason: You 'string' the ball, so there's no follow through.
It's a bit hard to describe, maybe you should google basketball shooting techniques. I have a book from a coaching course I did when I was 16 (2 years ago), maybe buya book?