Let's get started.
Step 1: Gather your materials.
Step 2: Assemble your workspace and tools
1. A hammer, preferably a claw type.
2. A handsaw of some type. Here I'm using a hack saw but it would probably be better to use a fine toothed wood saw.
3. A pencil for marking.
4. A screwdriver or crowbar for preparing the wood.
5. Nails. You will probably need some short (about 2 inch) and some longer (3+ inch) nails.
6. A pair of pliers to help pull nails.
Step 3: Prepare your wood.
You want to make sure you have enough of the right size of planks for this. Separate them into piles. I used 4 planks per side along with enough wood to nail at each end.
Step 4: Assemble the planks into sides.
Do this 4 times and you should get something that looks like this.