Seal the pebble tile after the adhesive has completely dried. This action will prevent the pebbles from absorbing the grout color. Allow the sealer to dry.
Dip your grout float into your grout, and apply it to the pebble tiles by pushing it into the spaces between the pebbles. Work slowly when doing this to fill in all cracks and crevices. When you have finished, the entire pebbled area will be literally covered with grout.
Allow the grout to set up and dry for 20 minutes.
Dip your sponge in the bucket of water and wring it out until it is damp. Begin to wipe away the grout on top of the pebbled area. When the sponge becomes full of grout, rinse it by dipping it into the water bucket.
Completely clear off all the grout from the surfaces of the pebbles, but don't wipe hard enough to remove any grout from the spaces between the pebbles. Allow the grouted surface to dry for 24 hours.
Apply sealer to the grout and pebbles.