Here is my answer for your question on 'shasthi Vratham'
Shasti Vratham or Skanda shasti is an important observance, which is dedicated to Lord Muruga. It is observed in the month of Aippasi ( in tamil) and most people observe fast during the 6-day period.
There is no common method in fasting for shasti vratham. There are only some basic rules which is followed by all the devotees.
1. Non-vegetarian food is to be avoided during this period.
2. You can avoid Garlic and onions too.
3. Visit the temple of Lord Muruga.
4. Read Kanda Shasthi Kavasam, Subramaniya Bhujangam.
5. Some people eat only one time either day time or night.
6. You can have fruits.
All these fasting are meant for clean the body and get rid of unwanted toxic elements. The fasting ends on the sixth day.
Vrat in Sanskrit means 'vow'. Vratam should not be misunderstood as mere fasting. By observing vrat, a person is trying to purify his mind and soul. This brings discipline in our life.
It was a great information for me,thanks.