all you need is 3" 2" wood (get plained its smoother to work with) and plaster board. You need to measure the width and length of the ceiling. First you will fix the 3" 2" all the way around the room at the height you want your new ceiling making sure it is level (draw a line with a spriit level around the room) then you need to measure your plaster board and fix 3" 2" again across the room so that you can fix the plaster board to it. It's better if you have 2 people doing this and make sure the plaster board is fixed all around so that the plaster fixes to it and the board doesnt move when plastering. good luck