Shower Stall Floor

I am building a shower stall in a new addition which will have a ceramic tile floor. I need to find out what the material(s) under the tile needs to be and what thicknesses they need to be. I presently have 3/4 T & G OSB over 2×8 lumber at 16 OC in place and nothing else. I am an amateur on my first try and would greatly appreciate any insight you could provide me on this one. Thank You