Print the image that you have decided to use. Have your kids paint the board in the color of their choice. Allow the paint to dry then add the paper to the board, making sure it is centered and straight. Add two nails around the edge of your image and through the paper to hold into place. Be sure to use nails with a large head. Do NOT put the nail all the way into the board. The nails should stick up so you can wrap the string around them. Use a pencil to mark approximately every 1/2 inch all the way around your image. Older kids can now take over and nail on every pencil mark. Again, make sure they are using nails with heads and that they make sure all of the nails are poking out of the board at around the same height.
When you are finished inserting the nails, it will look like the picture below. If you have younger children, please do the nailing for them and allow them to work on the string in the next step. NOTE: We decided not to add nails to the inside of the tires on this image. My son did all of this nailing himself and was so proud. Yes, there are some that look crooked. In the final product, it really does not matter so just go with it. Kids' crafts are full of imperfections so resist your urge to correct.
You can now rip away the paper from the board. You are left with a sea of nails and the kids are ready to wrap some string.
Young and old alike will love adding string around the nails. In and out, around, zig-zag, any combination they can come up with! Start on any nail and knot your string. Then work it around until you are happy and knot it off on your last nail as well. Make sure to keep the string taught in order to get the proper results.