Figuring out which bands are compatible is probably the hardest part of changing your Apple Watch band. The actual process for doing it is remarkably straightforward, compared to the special pins and other hardware that traditional watches often require. In fact, the main consideration is having somewhere soft to place your Apple Watch face-down, since you don’t want to scratch the cover glass. You could use Apple’s own microfiber cloth, but any clean, lint-free cloth or mat should suffice.
On the underside, next to the edges of the bands, there are two buttons. Pressing down and holding a band release button allows you to slide the band across, out of the groove in the Apple Watch casing. It can be a snug fit, so it may take a little trial and error to get the pressure and angle right.
To install a new band, meanwhile, the important part is to make sure the text on the band is facing you: it should be facing in, toward your wrist, when you wear the Apple Watch. Then, it’s just a matter of sliding in the new band until you feel it click into place; if you listen carefully, you should be able to hear that latch click, too. If your band isn’t latching properly, Apple suggests gently sliding it left and right until the mechanism engages properly, or failing that, centering it in the groove and then carefully wiggling it up and down until it clicks.