I learned this when I was 3 or 4 and my mom taught it to me.
Step 1: The 1st Fold.
All you need is a piece of printer paper. (8.5" x 11")
I prefer to fold it in half the long way so when I do the next step, it won't come out incorrectly.
Step 2: 2nd Fold.
Now fold the edges down so that they are on the middle fold you just did.
Step 3: Folding It Down.
Now fold the entire thing down so it is about 1" from the bottom of the paper.
Step 4: Folding Down the Middle Again.
Now fold the edges to the middle of the paper.
Now you should have a triangle at the sticking out.
Step 5: Fold Triangle Up.
Now fold the triangle up so that it is over the thing we just folded.
Step 6: Back
Now fold the entire thing in half so it looks like a right triangle.
Step 7: 1st Wing.
Now fold one side over so that it lines up with the other side.
Step 8: 2nd Wing.
Now repeat the process on the opposite side.
Step 9: Done!
Open up the wings and now you're done!!! Just throw it and have fun!!!