Summarize this article:

Copper rivets with washers tend to be larger than your everyday rivets. Make sure when you punch the hole that it’s big enough for a wider rivet post to get through. It should be big enough that you can push the rivet post through the leather but not so big that it slips right through. You should have at least 1/8 inch (0.3 cm) of rivet post above the surface of your leather. Push the rivet up from the bottom of the leather. Flip your leather over so you can see where the post sticks up through the leather. Set the washer over the post so that it’s flat against the leather. The anvil should be big enough to accommodate the piece of leather you’re working on. You should be able to work on the rivet on a flat surface. A copper rivet setter is silver, and is almost shaped like a lighter. On one end, you’ll see a concave circle, with a smaller, hollow circle next to it. Place the setter over the rivet post and on top of the washer, making sure the post goes into the hollow circle on the setter. You might need two or three taps to make sure everything is set. Don’t pound too hard, as this can ruin the rivet. When you’re done, the washer should be completely flat against the leather. If you notice that the washer seems to be higher on one side of the post than the other, give it another bang to make sure it’s set all the way around. With the same mallet or hammer, pound down on the post a few times. You should hit the setter fairly hard for this step, because what you’re doing is getting the post to expand and flatten out. This will keep the washer in place and your rivet secure.

Summary:
Punch a hole in the leather. Push your rivet through the leather. Set the washer. Set the leather and rivet on an anvil. Set up a copper rivet setter. Tap on the setter with a mallet or hammer. Set the concave section of the setter over the post.