Step 1 - Measure the Area
In order to install tile over cement board, you will need to first measure the room. Use the tape measure and get the dimensions of the space. Multiply the dimensions together to give you the exact square footage of the room. Add 10 percent to this figure to allow for waste and cutting. This will tell you how much tile you should buy for the job.
Step 2 - Determine the Center of the Room
Before installing the tile, determine where the center of the room is. Use the tape measure to determine where the center of each wall is. Use a chalk line to mark where the center of the room is.
Step 3 - Apply Thinset
Start at the center point of the room and apply some adhesive to the floor using the trowel. Make sure that you spread it out evenly over the floor.
Step 4 - Place the Tile
Once you have some thinset spread out on the floor, place a tile directly in the corner of the two chalk lines that you snapped. Starting from the center point of the room will create a more balanced look for the tile once you are finished. Press the tile down into the thinset firmly and make sure that it is level.
Step 5 - Spacers
In order to determine the proper distance between tiles, you need to use tile spacers. Tile spacers come in a variety of different widths and will determine the grout line width. Place a tile space are on each corner of the tile.
Step 6 - Placing the Next Tile
Once the spacers are in place, you should set another tile directly up against them. Press it down into the thinset and right up against the tile spacers. Continue applying thinset to the floor and using tile spacers to place subsequent tiles.
Step 7 - Cutting the Tile
When you get to a wall or a cabinet, you will need to cut the tile. Use a wet saw in order to make your cuts. You can measure the exact size that you need with your tape measure and then make the appropriate cut with the saw.
Step 8 - Allow to Dry
After you have finished laying the tile, let it dry overnight before walking on it.
Step 9 - Grout
Step 10 - Cleaning
After the grout has been applied, use a bucket and sponge to clean the tile. This will remove grout that is left on top of the tile and help smooth out the grout. Allow the grout to dry completely before using the tile.
selected from: https://www.doityourself.com/stry/how-to-fasten-cement-board