Check what kind of golf balls you are using! The best golf balls for making much backspin are the most expensive ones, such as Titleist Pro V1. Budget alternative is for example Wilson dx2.
Check the grooves on your wedge! Drag your thumb nail across the grooves. Do you see any nail residues? A good wedge with sharp grooves has nail remains. I recommend Titleist Vokey or Ping wedges.
The proper technique for generating backspin is simple. Hit the ball at the sweetspot of the wedge. A tip to see if you have managed to hit the sweetspot, buy impact tape at your PRO shop.
Check that the wedge is clean from dirt, especially the grooves. Check that the golf ball is dry and no dirt. Check that their are no grass between the club and ball.
Even after one shot the grooves must be cleaned! Otherwise the golf ball will skid over the grooves with less spinn. This can also produce the unwanted "flyer"
A Vokey wedge that has been cleaned from grass and dirt.