Why my car is overheating when I just got my hoses changed.

It could be several things, if you are sure there is no coolant leaks (have the system pressure tested to ensure there are no leaks), do you hear the electric cooling fan come on? It could be a stuck thermostat. It's had to just guess without being able to do basic diagnostic tests to see what is wrong.

You could have air in the system and you may just need to top off the coolant again and run the vehicle to make sure the fans cycle on and off and on again. The shop you repaired it at should perform this service at no additional charge to you, make sure and contact them.