1) your father has 1/5th share in farm land . better enter into deed of partition for division of said land by metes and bounds
2) your uncle can execute sale deed in respect of his 1/5th share in your favour
3) the sale deed has to be signed by your uncle as seller and you have to sign it as purchaser of said land
4)it has to be duly stamped and registered
5) contact a local lawyer