The following is the method of performing Ghusl:
1. Make the intention (Niyyah) and recite "Bismillahir Rahmanir Rahim" and wash both the hands up till the wrist three times.
2. Wash private parts (if they are not clean).
3. Then wash the body part where there is any kind of dirt/filth.
4. After that rub hands with mud (or soap)
5: Perform Wuzu.
6. If the already used water has collected at that place, then do not wash the legs there, move aside a bit, where there is no such problem and wash it after the Ghusl is finished.
7. After Wuzu, wet the hair completely and pour water on head.
8. Then pour water on the right shoulder, then on the left in such a way that the body is wet completely and water should drip from it
9. Rub the body with hands (This is washing the body for the first time).
10. Similarly pour water for three times, first on the head, then the shoulders so that the body is washed three times.
Ghusl is done.
Some important points:
If a person who is in a state of ritual impurity has removed the actual filth (Najasat Haqiqi, which means physical filth and uncleanliness, which may or may not be visible) from his/her body, then those drops of water which touch his/her body are called Used Water (Maa Musta’amal). The ruling about such water is that it itself is pure but cannot purify anything. For this reason, a bath with only Used Water is not correct. If Used Water is mixed with Pure Water (Maa Khalis), then bathing and Wuzu with such water is permissible; provided Used Water does not exceed the Pure Water.
Obviously, the drops of water which fall into the to-be-used water are less than Pure Water. For this reason, if drops of Used Water fall into the vessel of Pure Water, bathing or Wuzu with that water is permissible, as those drops of water that not Dirty (Najas). If the dirt/filth on the body has not been removed yet and while bathing, those drops of water mix with Pure Water, then bathing or Wuzu with such water is impermissible. As given in Durre Mukhtaar Vol. 1, Kitab Ut Taharah, Pg. No. 134.
Translation: As long as Pure Water is more than half of the water, then purification with that water is permissible. Otherwise it is impermissible.