The easiest way to use these products is firstly to determine the depth required to achieve a level. This can be done with a decent length spirit level and some batten plus a set of various thickness packers. Then divide the surface area into manageable areas using batten such that all sides are contained by walls or a batten. The packers can be layed at the edge at the height you have measured as required to achieve a level. Secondly you need to mix sufficient preferably in one batch to fill the area you have sectioned off....if not in one batch them someone else needs to be helping you mix so that you can deal with the first pour whilst another batch is mixed. Never mind the instructions on the bag.....the stuff needs to flow so keep adding water until it is creamy. The floor needs to sealed with PVA and going off time for the mix is influenced by ambient temperature and airflow so do it in the cool of the morning or evening rather than midday on a hot day. The mix should flow by itself but you can speed it up with a flat trowel. Fill the sectioned off area with mix until it is level with the top of your packers. Let it go off before removing the batten and packers. Section off the next area in the same way as before.