Some term defns. The tome that came with your camera will likely refer to the aperture in f-stops. Things like “f/2.8” and “f/22”. f/2.8 is a larger aperture than f/22. When you “stop down” you move from a large aperture to a smaller one – f/8 to f/11 for example. It gets confusing b/c the numbers increase as the aperture decreases.
By selecting smaller apertures, your depth-of-field increases – f/22 has lots of DOF, f/2.8, not so much.