very easy,try this.
1) Remove every piece of garment on your body.
2) From outside the bathtub, place your first foot into the empty bathtub first.
3) Then slowly bring your naked self into the tub by lifting your second foot into the bath tub, both time holding on to any good support like a metal handle or place a hand on the wall.
4) By now, you should be standing firmly inside the tub.
5) Next, turn around to face the faucets and lower your whole body by squatting down gently.
6) Once in this position, place your two bottoms gently onto the cold bathtub floor to achieve a sitting position. Put the water stopper onto the drainage hole or turn the knob or level on some newer system.
7) Then, reach out to the faucets and turn the water on. Make sure the water is just luke warm and not too hot to scald the vital parts of your body.
8) Lay back and stretch your legs.
9) Wait for the water level to fill up to your chest level in this position. Once the level is reached, turn off the tap(s) .
10) Now you can relax and start eating or reading in the nice bath.
PS: Getting out of the tub is the reverse of the above steps. Except you have to make sure you empty the tub and dry yourself within the tub first before attempting to get out of the tub.
Good Luck