Measure the tops of your desk and dresser. Use these measurements to purchase a mortar bed that will fit the top perfectly. The mortar bed can be just 1/8 inch thick.
Secure the mortar beds to the surfaces by spreading Portland cement paste with a trowel on the dresser and desk top and pushing the mortar beds into place.
Arrange your tiles on top of the mortar beds. Use 1/8 inch tile spacers between each one to represent the tile joints. Mark any tiles that need to be cut.
Remove a small section of tile at a time and cover the backs with a thick mastic using a rubber spatula. Place each one back over the mortar bed and press lightly.
Check your marks for the tiles that don't quite fit, and use a tile cutter to make the necessary cuts. Apply them to the mortar bed using the mastic. Wait 24 hours for the tiles to set before proceeding.
Spread grout over the tiles on the desk and dresser tops using a rubber spatula. Excess can be taken off with a rubber scraper and then a dampened rag. After 48 additional hours of curing, your desk and dresser tops will be officially decorated.