You need to find an old speaker that still works and remove it from its enclosure-preferably a good brand name but any speaker will work. Just make sure it can handle the power your amplifier puts out. Then you cut hole in top of can and on side of can for the speaker and speaker wire terminal block(see drawing)
Step 2: Prepare speaker for installation
In this step you will hook up the speaker wires from speaker to terminal block, add insulation to bottom of can to dampen sound and glue speaker to top of can.
Step 3: Start listening
Now you hook up your "Bubba Sub" to your amplifier or stereo and start listening to your tunes.