If you want to add an alternator, it will require fabrication on your part. First remove the black plastic cover on the engine, Passenger side, under the cover should be the flywheel you will notice in the center there are four threaded bolt holes you will need to fabricate a pulley to bolt on here. The black plastic cover should have a Knock-out to allow the belt to pas through it. The alternator is mounted in front of the engine.

Here is an example of an alternator:

( https://www.ebay.com/itm/NEW-CHEVY-MI...5e0f1d&vxp=mtr)

Built a bracket that mounts the alternator like an old Chevy. On solid side that will pivot and the other a slotted arm to allow the belt to be tensioned. Alternators like the one above are internally regulated, however they require a 12 volt switched circuit so that the alternator can "sense" the voltage in the circuit. They also usually have a wire that runs a light to indicate alternator failure "no charge". Wiring diagrams can be found for the alternator once you pick one, but it should be small, as the engine is small, and don't use too big of a pulley to drive the alternator. This will rob your engine of power.