Sheikh `Abd Allah b. Sardâr , lecturer at the `Umawî Mosque in Madinah
A ghusl must be performed by any person after completing the monthly period, after ejaculation, or after sexual intercourse. It is preferable but not compulsory to perform ghusl in the manner that the Prophet (peace be upon him) performed ghusl.
In brief, as extracted from Sahîh al-Bukhârî and Sahîh Muslim: wash the hands, then the private parts with the left hand, then wash the head while passing water through all the hair, then wash the body starting with the right side and then the left.
When you perform ghusl, you should start with your private parts. Then you should wash the rest of your body taking care not to touch the private parts. If you do it in this manner, you will not need to perform a separate wudû’.
If, however, you touch your private parts or break wind during the ghusl, you can continue with your ghusl and it will still be valid. However, you will need to perform a separate wudû’.
The minimum that is obligatory for ghusl to be valid is to have the intention for ghusl and make sure that pure water reaches every part of your body.
And Allah knows best.
Source: Islam Today