Traditional Grip is commonly used in marching snare music. It contains the right hand held as if it would possibly be matched grip. However, the left hand is held with the stick going in between the middle and ring finger. The end of the stick is in just on the outside of the thumb and pointer finger. Your left and right hand should be at an angle where they make an almost-perfect staight line down from your elbow. The sticks should be at a 90 degree angle.
Sometimes, drummers will commonly make the left-handed formation in their right hand. However, in marching band, this is wrong. If possible, try to switch between right and left hand traditional while practicing.