So i just bought a new tire today and i get home and put it all together and when i start to pedal it moves freely as if i was pedalling backwardson a normal bike, but when i pedal backwards it works as if it were going forward. I think the man at the bike store put the gear on the wrong side and i dont how to switch it or even if i can. What can i do?

Reading your post, I gather that you bought a new wheel and you suspect the shop installed a single speed freewheel backward.

If that's correct it's an easy fix. Turning the sprocket to the left will unscrew it. Wrap a rag or belt around it for grip and just spin it off, then flip it over and install it correctly. If it's on too tight put the wheel in the bike with the chain on normally. Tighten and backpedal with the brakes on and it'll loosen, then you can finish by hand.