Set camera to macro focus. Position camera to focus on (and lock on with green confirmation square) in the center of the shot with with nothing else around it. A coffee cup with writing or design pattern on it sitting on a empty table would be a good setup. Use an open aperture and fast shutter speed to reduce camera shake/blur. Get close, like 5 inches or so, lock focus, take photo and play it back. Look in viewfinder while rotating adjustment wheel located on the right side of it. Adjust as needed to bring pattern or writing into best focus.
Tip: place eye at EVF like you would if you were shooting. Practice a few times brining camera EVF up to eye before making final adjustment.