

Tayammum, You may perform your Salah by preceding it with Tayammum as a substitute for
Dry Ablution or Bathing Janaba
[Wudu or Ghusl e janaba].
When can you do Tayammum?
Allah SWT said in the Quran :
Believers, when you are about to pray, wash your face, your hands and arms up to the elbows, and pass your wet hands lightly over your head and wash your feet up to the ankles. After sexual intercourse, purify yourselves.
If you are ill, or are travelling, or have just relieved yourself, or have had intimate contact with a woman and cannot find water, then
take some dust and use it to wipe your face and hands.
God does not wish to place any burden on you, but wants to make you pure and to perfect His grace on you, so that you may be thankful.
[Quran 5 : 6]
In another verse of the Quran:
...If you are ill, are traveling, have relieved yourselves, or had intercourse, and cannot find any water, then find some pure dust and wipe your faces and your hands with it...
[Quran 4 : 43]
When a person cannot find water or sick and cannot use water. The use of water is likely to do harm, cause or worsen an illness, or delay the cure. In any of these instances, it is permissible to make Tayammum.
How to perform Tayammun?
1) First, make Niyyah (intention) in your heart that this act of Tayammum is for the purpose of preparing for Salah, and say: “Bismillah.”
2) Strike both hands slightly on pure earth, sand, stone, or concrete.
3) Shake off hands to remove debris and wipe the whole face.
4) Repeat step #2 and wipe the right arm down to the elbow (or only to the wrist) with the left hand and the left arm down to the elbow (or only to the wrist) with the right hand.
Watch video.