Download the PDFs, and print onto white text-weight paper. (If you are using a Mac, print the PDF using Preview instead of Adobe Reader.) Cut out each circle.
To make the circles into buttons, use a button maker (Badge-a-Minit has a relatively inexpensive one). Or, send your circles away to someone who will make them for you (Wacky Buttons is one such vendor; Busy Beaver Buttons is another).
To distribute the Friend buttons, download the PDF for the display card (see "With this Button" links). Print onto white card stock. Use a craft knife and a metal straightedge to cut between the crop marks. Cut the lengthwise center cut first, but do not cut all the way to the edges of the paper; this will leave the side crop marks intact for subsequent cuts.
To make it easy to insert the buttons in the cards, use a Japanese hole punch or a screw punch -- or even a push pin -- to make two small holes in the blank area. Then thread the pin of the button through the holes, and fasten.