Pre-heat the over (375 degrees), and cook the sausage (see my link for more info)
cook the lasagna noodles
lightly grease lasagna pan, and add a layer of lasagna
beat the ricotta with the lasagna with the hot water to make it spreadable, spread 1/3 of the ricotta over the noodles, spread 1/3 of the sausage and 1/4 of the cheese to complete layer .. then continue making layers
pour the remaining cheese and butter on top, then bake for 15-20 minutes. Let sit for about 10 minutes to cool and come together.