Part I – What grip should you be using? How to grip the handle?
The two-handed backhand does not have a magic grip you should be using for your non-dominant hand; however, a continental grip is the best choice for your dominant hand. Your dominant hand should be gripping the racket on the bottom end of the racket, whereas your non-dominant hand is placed right above it. Your grip for your non-dominant hand should be some kind of forehand grip – an eastern or semi-western grip is ideal. (See Picture above for a visual of the two-handed grip)
Once you have the two-handed backhand grip down, move on to the next step.
Note: Your non-dominant hand does about 60% of the work on the groundstroke.
Part II – Turning your body and proper footwork
Once you get into your two-handed backhand grip in the ready position, you begin the coiling phase of the stroke by stepping to the left with your left foot. As you are stepping to the left, take the racket straight back with the racket head pointed somewhat diagonally upwards where your left hand (for righties) and turn your shoulders far enough where your right shoulder is below your chin. Now once you have fully turned, step in with your right foot so that it is in front of your left leg to add forward momentum into your shot. (See Picture above for examples of the coiling and footwork)
You are now ready to move on to the swinging phase; arguably the most difficult part.
Part III – The forward swing phase and the follow-through
You begin the forward swing phase by dropping your racket-head below the ball (You properly achieve this by raising your right-hand above your left-hand). This is what gets you to point the buttcap at the ball.
Immediately after this step, uncoil your body (hips and core) to the net. As a result, your arm (Keep your non-dominant arm tucked to your side as this will prevent late contact) and racket will naturally accelerate forwards through the ball. Remember, the body is what swings the arm!
The follow through should be over your left shoulder if you are right-handed.
Check out video examples of Murray:
This is my guide on the basics of the two-handed backhand. Hope you find this helpful!