Gather your supplies.
Clothespins - I got a pack of 100 from Walmart for about a dollar. (Tip: when doing crafts, don't just go straight to the aisle where crafts and DIY supplies are. Go to where you would normally find these things. There were clothespins in the craft aisle at this same Walmart 24 for $2, but in the laundry aisle, they were 100 for $1. Be smart about making things, companies take advantage of all of us out there pinning away.)
Paint and brushes - I already had these. I wanted my pins to be different shades of green so it looked more realistic so I mixed black and white with them, but you can always just get one green if you wish. Just depends on the look you're going for.
Wire - I was going to use a wire hanger, but I couldn't find one in the house anywhere. No wire hangers! (Whoever gets that reference gets a prize.) So I bought this wire pack. They ended up being more bendy than I wanted but twisting them real tight helped build support enough to hold up some cards.
Bow - To top it off and make it festive!
Paint your pins.
Self explanatory. I only painted three sides so nothing would rub off on the wall but so that everywhere you look the pins are green.
Again, self explanatory. Make that sucker look pretty and hang it up. I made my clothespins go opposite ways for every other one so that cards could hang on the inside and outside.