Sew a simple oilcloth wallet!

Step 3 Start creasing.

 Fold the 6x8 piece in half lengthwise, right sides touching. Crease down the middle with your fingernails so that it stays.

Then, at the edges opposite the fold, fold over a 1/4 inch strip of the right side onto the wrong side and crease again. You'll do this for both edges. 

For the 2.5x8 inch strip, you're simply creasing a 1/4 inch strip of the right side on the wrong side at top and bottom. :)

(The pictures should clear up any confusion!)