The Best way to spin the ball is by choosing the right equipment. First of all, one of the most important things is the golf ball. It is very difficult to spin a hard ball(Top flight, Pinnacle, Slezenger, Maxfli). I advise you to spend a little bit extra on a good soft golf ball like a callaway or Titleist Pro-V1 Golf ball. Obviously this is a little bit more expensive but the better quality golf ball the better performance. Also it is important that you use a wedge that has new grooves. If your grooves are worn out, it will be difficult to succesfully spin the ball. In terms of the swing, you want to hit down on the ball and pinch the ball between the ground. You should swing down on the ball and aim to hit directly behind the ball where the ball and ground meet. This will pinch the ball between the ground and club(considering you are hitting down on the ball) which will cause the ball to shoot out with a lower trajectory but more spin. In analogy it is similar to squeezing a peanut between two fingers. If you squeeze on the end the peanut, it will be pinched inbetween both fingers before squirting out with a line drive trajectory. Similarly hitting down on the golf ball and squeezing the golf ball between the ground and club will cause it to squirt out with a line drive trajectory and a lot of back spin!
Good Luck!!!!!! Feel free to ask any questions!