Measure the size of the countertop with a measuring tape. If the counter will be flush, use the exact measurements. Otherwise, add an inch to the length.
Cut the underlayment fabric to fit the counter. Roll out the fabric and trim it to fit with scissors. Staple it into place on the counter.
Spread out the mortar on top of the underlayment fabric. Use a textured trowel. Trowel it on with the smooth side, then use the textured side to score the surface and smooth it out.
Place your tiles onto the mortar. Press each down firmly. Use grout spacers on all sides of the tile.
Apply grout to the tile. Remove your spacers as you work and fill in the areas between the tiles with grout. Immediately wipe off the excess with a soft, damp cloth. Allow the grout at least 24 hours to cure before using the surface.