Selling house.. registered will

my maternal uncle expired few  years back. He was not married. He has registered will in which he has given his house to my mother, my maternal aunt and my cousin (some time back he also expired and his wife and childred are there) . Now we all agree to sell the house. What would be procedure for that. Do we have to get house transferred first or can we simply sell the house. Please explain in details.
Sudeep