*** Tayammum ***

Make Niyyah (intention) to perform Tayammum (Niyyah
is the name of the intention of heart and pronouncing
it verbally is better. For example, make intention in these words: ‘I am performing Tayammum to purify myself
from impurity and to make myself eligible for offering
Salah).

Read بِسْمِ اللّٰه and, with fingers spread wide open, hit
hands on some pure object that is earthen in nature
(e.g. stones, limestone, bricks, walls, soil etc.) and drag
the hands back and forth on that object. If hands
become over-dusty, reduce excessive dust by jerking
hands. Wipe entire face with hands such that no part of
the face is left unwiped; Tayammum will not be valid if
even a part equivalent to a hair is left unwiped.
Again hit hands on that object like before and wipe
both arms from the fingertips up to (and including) the
elbows. A better way to do this is to first wipe right hand
with inner side of four fingers of the left hand, leaving
the left thumb, starting from exterior side of fingertips
of the right hand and dragging on exterior side up to
the right elbow. Then, wipe with palm of left hand from interior side of right elbow up to the right wrist dragging
left palm on interior side. Finally, use the inside of the
left thumb to wipe the back of the right thumb. The left
arm should be wiped in the same manner using right
hand. (Al-Fatawa Tatar Khaniyyah, pp. 227, vol. 1)
And if wiping is done with palm and fingers jointly,
Tayammum will still be valid whether traversing is
done from fingers towards elbow or vice versa. But this
would be contrary to Sunnah. Tayammum does not
require wiping of head and feet.

~ Faraid of Tayammum ~

There are three Faraid in Tayammum:

1. Intention
2. Wiping hands on the entire face.
3. Wiping both arms including the elbows.
(Bahar-e-Shariat, pp. 353, vol. 1, part 2)