First, I remove the backing from the disk and attach the washer. Even though the disk has adhesive on it, I still apply super glue, because I've had the assembly come apart when I didn't glue it first.
I hold it together for several seconds, then I drive a nail through it from the bottom. Note the use of a magazine to prevent holes in my kitchen table:
The finished product looks like this:
And here you have it with the mini attached:
Easy and cheap, which is how I like my miniatures gaming.