Make sure the existing concrete subfloor is clean, free of dirt and debris, and completely dry.  Protect walls, stair cases, etc with painters tape.

You will prime the exisiting concrete twice with a polymer that is mopped onto the floor.  Then mix the overlay material according to instructions.  This usually consists of mixing polymer, color agents, and concrete materials.

This is applied evenly across the floor and dried.  Then the overlay is sealed.