Your basic materials are cork mats or trivets, metal mending plates, screws, screw driver, and a small d-ring hanger. You can get a lot fancier with paint and ribbon but this is the original simple idea.
Place the cork pieces in the position you want them to be in, use the mending plates and screws to connect them together.
Attach the d-ring hanger at the top of the board, and hang it where you want to use it. I used a little hot glue to hold the screw in place for the hanger, it also keeps the screw from scratching the wall. I also used trivets because at Ikea they are pretty thick and inexpensive. Sometimes cork at a regular department store can get expensive.
This is where I hung one of the boards I made. It hangs on the corner of my corner cabinet, no irony intended!