how to relax

If your wrist is not dropped you will never be able to relax.

Also the grip is important. Try to shift to a less tight grip by shifting your hand downwards relative to the blade face.  

The next problem is using arm only strokes. This will definitely cause you to have a tense stroke. Use your waist rotation, and weight transfer + pushing off your right leg for power, not your arm. 

Once you done all the above, I'm quite sure if you have a correct stroke, you will have a relaxed grip.

One tip after mastering all this. Let your index finger rest on the rubber, not pressing it, you can even have it leave the rubber for a while, then when you're hitting the ball, use your index finger to give the blade a nudge forward. This resulted in a MASSIVE increase of power and relaxation for me. But it's not recommended for beginners :P

don't bother if u can't get the other parts right. If you don't understand it, you probably shouldn't be using it anyway, it probably will mess up your timing and ur stroke.