|Covered snaps are a lovely detail that is very simple to add to your garment. Covering the snap makes it much less obvious, and can make it almost invisible.
Snaps are not often called for in pattern instructions, and not used too often in RTW anymore, but there is nothing that will assure the exact placement of an edge or closure like a snap. You need something else to take the strain of a waistline for example, but a hook to hold it, and then a snap at the very edge or corner, so that the band sits perfectly is a special touch.
To cover your snap, cut a circle of the fabric you want to use. Lining fabric is often used, and a thin fabric is best. (If you suspect your fabric may be too thick, put a piece of fabric between the snap halves and try to snap them. If they won't stay shut reliably, try a thinner fabric.) Poke the "point" of the snap through your fabric. You may have to push aside the threads with an awl or large needle, or it may just go through on its own. Fold the fabric to the back of the snap and take a few stitches to hold it in place. Place your snap on your garment and stitch in place. You may stitch through the snap holes and the covering fabric, or just through the fabric. I usually try to hit the holes as well.
When you have this done, cover the female half of the snap the same way. You do not have to make a hole in this fabric circle. Put on your garment and put some chalk on the snap protuberance. Push it against the garment where you want the other half of the snap, and it will mark the correct position. Attach the second half of the snap, and there you are!
This is a really good method to use for a secure closure when you are using buttons that are too large for rational use. Click Here for a photo of such a button which has a covered snap inside the closure.