Karva chauth

Fill water in the kalash and keep it in front of the deities.Burn a lamp over it in a diya which covers the kalash.Start the pooja with the shlok of ganesh ji

Gajananam Bhuta Ganathi Sevitam
Kapittha Jambu Palasara Bhaksitam
Uma Sutam Shoka Vinasha Karanam
Namami Vigneshwara Pada Pankajam

Sri Vakratunda Mahakaaya
Soorya-koti samaprabha
Nirvighnam kuru me Deva
Sarva-karyeshu Sarvadaa

Mooshika vahana modaka hasta
Chamara karna vilambita sootra
Vamana roopa Maheswara putra
Vigna-vinayaka paada namaste

Ekadantam Mahakayam
Lambodara Gajananam
Vigna Nashakarma Devam
He Rambam Prana Mamyaham

After this offer prayers to shiv-parvati...offer prasadam,say stories of karva chauth with akshat on your palms..and exhange karvas among each other.

After offering prayers and pooja, offer water to the moon by taking seven rounds and on each round take a strand of your own hair,one stick of the grass and touch it with your nose pin and drop water over this from the nozzle of the kalash, take a round and say:"He karva rani !arag tohar,suhaag hamaar...."After this you can have water along with some sweets and also take sindoor from gauri ji.