Eyelets come with two different ends.
The front and outwards facing side of the eyelet is the taller side.
To attach, decide where you want your eyelet. Mark it to the size of the center hole.
Cut the hole out.
If it does not close the first time, re-position and try again.
Stick the center of the eyelet through the hole making sure to have the front and outwards facing eyelet on the outer side of your fabric. Put the flat disk in your kit under the frontwards facing end and the hammer end on the back. Gently tap the hammer end with a hammer until the eyelet is closed on itself.