You probably ought to confirm that it's really a sub. Find its free-air resonant frequency by sweeping from about 10 Hz to 200 Hz or so, watching the impedance. The resonance will be evident where the impedance peaks.
Using the resonant frequency, go to a website that tells how to design the enclosure. You're still missing a lot of "important" information, but you might end up with a listen-able enclosure.
If it's really a sub woofer, you can safely drive it to the point where the speaker travels about half of its available excursion, at the minimum frequency.