During the days before colour photography, you had to affix photo corners to an album page with glue. When gummed photo corners became available, it made the job easier, but you still had to lick or otherwise moisten the backs. Modern photo corners come in self-adhesive versions. Not only are they easier to use, they come in far more colours than just basic black: white, gold, silver and a rainbow of brights. Some self-adhesive photo corners are even clear, so your entire photo remains visible.
Lay a group of photos right side up on an album page. Move the photos around on the page, trying different arrangements. Leave room to write, if you plan to label the photos on the album page. Leave the photos in place on the page once you're happy with their placement.
Peel one of the self-adhesive photo corners from the sheet. If the photo corners are packaged loose instead of stuck to a sheet, peel off the backing, exposing the adhesive.
Lift one corner of a photo slightly, but don't move or bend it. Slip the photo corner over the lifted corner of the photo. Hold the photo in place with one hand, and press the photo corner onto the album page with the other. Repeat with the other three corners of the photo, and then with the other photos on the album page.
Make sure you use a photo album with paper or pasteboard pages. The sticky album pages with clear plastic covers aren't meant for use with photo corners. Use acid-free, archival photo corners and a photo album with acid-free paper to protect old black and white photos.
Don't affix self-adhesive photo corners until you're sure about their placement. If you try to move them, you may tear the paper album pages.