You don't need to be 6 feet tall to be great at heading. In fact, the most important factor is not how tall you are, instead it is the technique.
The most used heading technique in soccer is the standard or defensive header. Regardless of your position you will always need to use the defensive heading technique in a soccer game.
When performing a defensive header you need to arch your back, collect enough power and hit the ball with your upper forehead. A defensive header can be very effective in situations where you need to push the ball in the back of the net, pass or redirect a flying ball or as a defensive clearance.
The key to learn this heading technique is to hit the ball with your forehead just underneath the ball.