Flams are the drumming equivalent to grace notes on other instruments. They are meant to be an embellishment to the more prominent note. They are played just before a note and are to give the main note a different sound. There is usually very little space between the flam and the main note. Open flams are played with more space between the flam and the main note to give another type of sound. The flam always hits the drum before the main note, so it makes sense to have the stick playing the flam closer to the drum head than the stick playing the main note. An exercise you can try to demonstrate this idea, is to hold your left stick about 1 inche above the drum head and hold your right stick about 6 inches above the drum head. Let both sticks drop at the same time. The left stick will naturally hit the head before the right stick and you will play a flam. You can sometimes use the height of your sticks to play flams exercises that naturally help you play better flams. When I was first learning to play snare drum, my teacher noticed that i was playing flams backwards: I was trying to quickly play the flam note with the wrong hand. Playing in that way made it very hard to play flams. Once I learned what I was doing wrong, playing flams and drumming in general became much easier. Try to use stick height to help you play better flams. Look at your hands and make sure that the way your are playing makes sense and isn't going against the natural flow.
Here's a YouTube video on how to play a flam.
Brad Hill is a drum/percussion instructor in Berks County, PA ( Shillington, PA ). Go to Drums1On1.com (Drums 1 on 1) and submit the Contact form for your free consultation to determine the best lesson plan for you. I offer drum lessons and percussion lessons. In person and online lessons available.