Easy stenciled bag
You can find the stencil on http://www.google.nl/imgres?q=punk+girl%3B+stencil&um=1&hl=nl&sa=N&biw=1440&bih=781&tbm=isch&tbnid=cAX6kvzxy6C8xM:&imgrefurl=http://thumbshare.deviantart.com/art/Just-you-and-me-punk-rock-girl-21654278&docid=nGomvC9GvH4o7M&w=150&h=115&ei=6JKKTv_JEcqhOt3_3c4F&zoom=1&iact=hc&vpx=658&vpy=208&dur=1831&hovh=92&hovw=120&tx=87&ty=56&page=1&tbnh=92&tbnw=120&start=0&ndsp=33&ved=1t:429,r:3,s:0
I thought it was too small so I changed that on Paint :)
When you're sure you'r stencil is big enough, print it, cut it out on a cuttingboard with a stanley knife/cutting board knife.
Put a plastic bag in the white cotton bag, yo make sure the paint wo go on the inside. You can also use plastic bags to make sure the ground you'll be spraying the bag on won't get painted too x]
Use tape to make sure the stencil stays on it's place. Now you can spray paint it.
When you're done with that, let it dry for a nice long time :)