This is a pretty broad question. Do you mean a shower with a curb, or one you could roll a wheelchair into?
In any event, a waterPROOF liner must be under the tile. There are a number of special requirements.....the subfloor must first be pre-sloped to allow water to run to the drain. Then the waterproof membrane goes down...PVC, copper, or lead. These materials take some knowledge and skill to put down. Then a mortar sub-base goes down, and the tile on top of that.
The membrane must be continuous up and over the curb, and about 8" up the wall.
A good reference is the "Ceramic Tile Handbook" from the Tile Council of America ( tileusa.com)
Another excellent resource is the tile forum www.johnbridge.com
I do recommend that you get some books and do some study. Right now you don't even have a basic understanding to ask relevant question. There is a lot of help available here on the internet, but we can't build it for you.. You have to take the lead.
By the way, there are some more modern waterproofing systems than those I mentioned, so if you go into a tile specialty store, you can probably get some reference material and training about those.