Alex Fixed rear build

walked out of my "lbs" today with an alex DA16 rear wheel and took my buisness to a bike shop closer to home to pick up the cog and lockring, got some cheap track cog for 30 aus and they were out of loc rings, no big deal as i could just pick one up from the bike shop near school tommorow, the hub on the wheel has one side with small threading and the other with the larger threading that the track cog is on no reverse threading for a loc ring on either side

so two questions..
what do i do to get this locked up?
and what is the smaller threading on the other side used for?

You have described a Flip-Flop hub ...

The side with the smaller, reverse-threaded portion is the side that the TRACK COG is supposed to be mounted on ...

The lock ring will be reverse threaded & fit on the mystery portion of the hub.

The side you apparently have chosen to temporarily mount the cog is the side that a Freewheel is typically mounted on.

nope, one side is all small threading the track cog would not be able to screw onto it... and the other side is all larger threading which the cog does screw onto

Oh, then you probably have a BMX hub ... or, something more exotic!?!

It's considered dodgy, but you can use the lockring used for the non-driveside of an OLD style, adjustable English threaded Bottom Bracket ...

Loctite is often recommended ...

Instead, I would cut a washer from a plastic laundry detergent jug, or equivalent ... and, probably use some tub-and-tile adhesive caulk to "fix" the makeshift lockring.