According to the Hindu calendar, Shatila Ekadashi fast is observed every year on Ekadashi of Krishna Paksha, Magh month. On this day, Til(sesame) is used in six ways. It is used in Ubtan, bathing, performing Havans, Tarpan, meal and donations. Hence it is called the Shatila or Shattila Ekadashi Vrat.

Significance of Shatila Ekadashi Vrata
Sins of a person are removed on observing Shatila Ekadshi fast with full devotion. Hence, while observing this fast a person should keep control on all his senses and should get rid of all his anger, ego, gossips and other sinful activities and devote himself to God. There is also a belief that by observing this Vrata a person gets place in heaven after death.

Shat-Tila Ekadashi Fast Procedure
Once Dalabhya Rishi asked curiously to Pulastya Rishi about the peoples on earth are always involved in different kinds of dissipation and sinful activities like gossiping about others, killing Brahmans etc., but still they get place in heaven. He further asked "Which donation or saintly work is done by them that they become sin free." Then Pulastya Rishi replied "Rishi, I am going to tell you a secret which no one knows in the heaven. Brahma, Vishnu, Mahesh and God of gods Indra also dose not know about this secret."
He said "as the Magh month begins, a person should wake up early in the morning and perform auspicious works after bathing. He should keep himself under control and meditate. A person should make 108 Uplay(patties) of cow dung mixed with Til and linseed in the Pushya Nakshatra. On Shatila Ekadashi of Magh Masa, a person should complete all his daily work and wear clean clothes. After that the fast resolution is taken and Lord Vishnu is remembered. If any mistake is committed while observing the fast, the person should apologize to Lord Krishna. Havana should be performed at night with the 108 Uplays. Jagran and Bhajan is done whole night. Next day, Lord is worshipped with incense sticks, Deep and Naivedya and then Khichdi is offered. If a person dose not have all the materials for Puja, he may use 100 betel nuts to worship and may perform Ardhaya Daan.

While offering Ardhaya the following Mantra should be chanted:-Krishna Krishna Kripalustvamagatinam Gatirbhav;
Sansararnvamagnanam Prasid Purushottam.
Namaste Pundrikaksha Namaste Vishvabhavan;
Subrahmanya Namasteastu Mahapurush Purvaj.
Grihanaardhayam Mayaa dattam Lakshmyaa Sah Jagatpate.

A person may also offer this prayer in the following way - O Lord! You give shelter to the poors. You are the restorer of people stuck in the ocean of this world. Hey Pundarikaksha! Hey Vishvabhavan! O Ancestor! Hey Jagatpate, I pay you my obeisance. I pray to you and Goddess Lakshmi to accept my Ardhaya. After this the person should worship Brahman and give him a pitcher full of water, an umbrella, shoes and clothes. In addition, Black cow may also be gifted to him, if in capacity. An individual observing this Shatila Ekadashi Vrat should give a pitcher full of Til to Brahman. The number of Til he donates that will be the number of years he will stay in heaven.