Concrete is plain and not particularly stylish or attractive to look at, but that is not how it has to be. You can decorate a concrete slab to make it more appealing. If you have a slab in the backyard that is used as a patio for entertaining, consider changing its colour or look so that it no longer resembles concrete. The task is not complicated and shouldn't take more than a day.
Wash the concrete slab off to remove dirt and debris. Let it dry out for 24 hours.
Apply tape to the concrete surface where you don't want the stain to coat. Make designs with the tape such as stripes, squares and other shapes. You might also consider using a stencil to cover parts of the patio and form designs or words.
Mix concrete stain and water in a garden sprayer in equal portions. Put the lid on and shake it up. Adjust the spray nozzle to a fine mist.
Coat the surface by spraying in a circle pattern. Do not spray back and forth unless you want to coat the concrete with a solid colour of stain. The circle pattern will allow you to miss spots and make it more natural. For a natural affect, spray over the concrete with three different colours in earth tones. This creates a stone-like look.
Wait for the surface to dry, then remove the tape. If you don't want the plain concrete colour where the tape lines or stencils were, but like the pattern affect, you have two options for covering it up. You can spray the concrete a solid light colour before you ever put any tape or stencils down. Or you can tape on either side of the lines after the fact and brush on a different colour stain.
To give the affect of grout lines and tile stones, use a masonry blade on a power saw and carve out the concrete along the tape lines.