it depends on what type of texture you are doing. The most common wall texture is called an orange peel. This is named for the the fine bumps that appear like the peel of an orange. If this is your texture you can buy an aerosol can at home depot for about $10. The can comes with simple directions on how to apply the texture and how long it takes to dry. The easiest way that I have found to apply it evenly is to test the spray on a piece of cardboard or something first. You can blend it in on the patch by moving the can slowly in circles and spreading it well beyond the actual patch area. This will help the new texture blend in with the old texture.