The procedure to keep all these fasts and worship Shiv is similar for all kinds of fasts, but in each case the Kathaa to be read or heard is different. Food is eaten once in the day. Cereals are permitted. After prayers to Shiv and Paarvatee one must read or hear the appropriate Kathaa. To appease Chandramaa one must wear pearls and silver. When inclined to give charity, one must give white things like rice, white clothes, conch shells, silver or pearls.

(3) Mondays in the Hindi Month of Shraavan
(July – August) is dedicated to Lord Shiv and Hindoo in North India observe Shraavan Maas Som Vaar Vrat. In this month, Shiv Ling is bathed with holy water from River Gangaa or water mixed with raw milk and Bilva (Bel) flowers and leaves are offered to the Shiv Ling. Fasting is observed from sunrise to sunset on all Mondays in the month. Married women observe the fast for a happy and long married life. Unmarried women observe it for getting good husbands. Men observe it for a happy and peaceful life. Those who observe fast eat only a single vegetarian meal. The importance of Shraavan Som Vaar is because it is believed that the Saagar Manthan (Churning of the Milky Ocean) took place in this month and Lord Shiv drank the poison Halaahal poison to save the world during this period. Offering milk to Lord Shiv in this month is considered highly auspicious. People also worship Paarvatee, Ganesh and Nandee Jee along with Shiv Ling on this day.

(4) 16 Mondays Vrat (Shraavan to Kaarttik)
One has to fast from morning till evening and do Poojaa. One should not eat salt, onions, garlic, non-vegetarian food etc. In the evening one should take the Prasaadam after offering it to God. One can recite Shiv Maanas Poojaa Shlok and Shiv Aanand Laharee. Read the Som Vaar Vrat Kathaa. Please see these links for 16 Som Vaar Vrat Kathaa
--  http://www.shaivam.org/siddhanta/fessomav.html
--  16 Som Vaar Vrat Kathaa

Though all Mondays can be observed as Vrat but there are some special Mondays when it is much more emphasized to observe like the Shraavan Som Vaar and Kaarttik Som Vaar. According to Skand Puraan, the Kaarttik (mid Nov to mid Dec) Mondays are more auspicious than the Shraavan Mondays.

Get up at the dawn, meditate on the Shiv. After taking bath and having done the morning twilight salutation, praying the Auspicious and Graceful Lord Shiv, worship the couples who are devotees of the Lord, chaste and loveful as the Divines couple Paarvatee Parameshawar themselves. Saluting those couples, offer them feast, the observer of this Vrat eats only one time food that day. If unable to do the worship, then one may go to the temple and salute and pray the Umaa-Maheshwar. Anointing the Lord with Panchaamrit and other pleasant substances, hailing the Lord offering Bilva leaves, not being money-minded offering the nice food materials to the Lord, sharing the food with the kind hearted devotees one eats the food. One may fast completely also.

How to Do Poojaa
To do Poojaa of Shiv either one can go to temple or can do it in his home. One should make a Shiv Ling of mud and worship it. It may be kept for 16 Mondays, or it can be made every Monday afresh. If it is made afresh every Monday, one should do its Visarjan on every Monday; but if it is made for 16 Mondays, it should be flowed in water the last day. If you cannot flow it in water it should be put in a cup of water, covered at least with 4-5" of water. When it is dissolved, that water should be poured in  tree roots.

Offer milk, water, chandan, Akshat (Chaaval), Haldee, (do not offer Kumkum except in the Shraavan month), Bel Patra, Aakade ka Pphool (a special flower which is offered only to Lord Shiv), fruits and other things as per your choice, also pray goddess Paarvatee and Ganesh. Then speak the Kathaa and Aaratee.

Some people do fasting this day eating only one thing, such as Choramaa, milk, Tulasee leaves (mik and Tulasee Vrat is a difficult one)

Vrat Kathaa
You can also see these links for Som Vaar Vrat Kathaa---
http://www.indif.com/nri/kathas/Somvar/solahsomkathaeng.asp
http://www.bhaktisangeet.com/vratkatha/somvar/somvar02.html
http://www.s-a-i.info/assoc_change/somvar.html
http://www.s-a-i.info/assoc_change/somvar1.html
http://www.s-a-i.info/assoc_change/somvar2.html
http://www.s-a-i.info/assoc_change/somvar3.html

Som Vaar Vrat Katha

From a Panchaang
This fast is done to get mental peace, wealth, children, and to get free from all kinds of afflictions. Start this fast from Chaitra, or Vaishaakh, or Shraavan, or Kaarttik, or Maargsheersh, and do it for 5 years or 14 years, or at least 16 Mondays. It is customary to start this fast from Chaitra Shukla 8th, Monday with Aardraa Nakshatra; or Shraavan's first Monday. The person should take bath with the water mixed with white sesame seed. After the bath chanting "Om Namah Shivaaya" one should worship Shiv and Paarvatee with white flowers, white sandal, Panchaamrit, rice, betel nut, fruit, Gangaa water, Bilva leaves. Then should offer Daan and Dakshinaa to a Braahman and eat food. Food should be only one time and without salt. One should finish (Udyaapan) this Vrat in the above months only. While doing Udyaapan one should do Havan of 1/10th part, and donate white things, milk, yogurt, silver, white fruits.