You Will Need:
A speaker (I got mine by taking apart an old computer speaker)
A pair of iPod earbud thingies you don't want back
A soldering iron or a bunch of electrical tape (I used the electrical tape but soldering would probably be preferable)
A wire stripper (you can use scissors for this if you don't have one).
Step 1: The Earbuds
Step 2: The Speaker
Cut the wires connecting the speaker to the container and the rest of the circuitry as closely as you can, so the wires still connected to the speaker are as long as they can be. As in my picture, one will usually be black and the other blue. Strip the ends of each of the wires about 3/4 of an inch back. There will be many little copper wires twisted into one if your speaker is like mine. There will be labels on the back where the wires are soldered on saying which wire is negative and which is positive.
Step 3: Putting them Together
Do the same with the red and green wires on the headphones and the negative, or black, wire on the speaker. If you're using tape, make sure that it is tight and secure before moving on to the next step.
(Sorry I don't have pictures for this step, which I know would help a lot, but I hope my instructions are clear enough to make it work)