Hey,New Jersey Herelisten im new to bikes,well rode when i was young,but found a cheap huffy cruiser in trash hooked it up,and cruisers are like caddilacs,any way when i back pedal to brake,my pedals force themselves foward by them selves,is it the coaster brake? and if so can i put any other back wheel on that has coaster brake? please help!!! Thank You!! Ride On.....

Welcome to BF!

If there is a small arm on the rear axle that attaches to the lower frame rail, You have a coaster brake.

If there is no arm, you might have a fixed gear (aka - fixi) bike where the wheel and sprocket are locked together. You brake with reverse pressure. Some folks actually like this kind of bike.

I'm sure you're local bike shop can either provide you with the parts you need to make it a coaster brake bike, Or will do it for you.

You could add a caliper brake kit like this to the bike if you want something that is a bit better:
https://www.bikezonela.com/product/o...t-319744-1.htm