Let's start with materials:
-Wood lopper
-Tree
-Saw
-Wood chisel
-Hammer
-1 Screw and Screwdriver
-Some type of bowstring (I used hemp cord (No, not the illegal plant))
(And this is my first instructable so give me any advice you may have.)
(and sorry that the background is a random room. it was raining the day i made this instructable.)

Step 1: Step 1 Cut the Tree

Find a tree with moderately flexible branches (I used Tulip Poppler)
Saw down a branch to suit your length, but the width should be about 1-1/2 inches in diameter. It's best to saw at the trunk.

Step 2: Step 2 Cut the Notches

Then, get a saw and cut slits on either side away from the "natural curve" of the branch. This will be where your string will be. These notches should be at the very top and bottom and should dig about halfway into the bow. There should also be at least 1/4 inch of where the wood stays. It should look sort of like a side view of a sofa.

Step 3: Step 3

Now its time to give the bow a little more flexibility. Take you chisel and hammer and chisel down the top and bottom sides of the bow, leaving enough room for a handle. This should be on the inside of the "natural curve."

Step 4: Stringing Your Bow

First, tie a loop at the end of your bowstring (a poachers knot will work well). Hook that around one of your sofa-shaped notches. Make another loop. Put the side of the bow with the first loop on the ground and push on the bow so it bends. Hook the loop around the notch. If the string is loose, un-string, tie a simple knot, and try again.