How do I write a letter to our panchayet for partition of our land??

Panchayat will not attend to family partitions.

Contact a local advocate, reduce the same in writing, maintain sufficient copies with each every co-shaers.

File application with the copy of such partition deed and pay prescribed fee and request them to mutate the property in your name (or Co-shares)

This is their usual routine business and they have to effect the mutation in their revenue records within a month.  After such mutation pay property tax, and that cash receipt disclosure your name for your record.

Seek guidance of local tutor.