front is easy -- lossen the brakes, then loosen the tire and change it.
back -- loosen the brakes and the chain. make sure the rear gears are similar to what you had before (# and spacing) and do the same as the front. i've never dealt with the gears in the back but ..... [the last rear wheel that i personally changed was on a 5-speed bike i used to deliver papers on my paper route about 30 years ago.]