slant six help!

i recently just got my car started a 75 duster. it wont idle for very long. its starts up and idles then it starts to chug slower and slower untill the whole car just stops. and after gas pours out from the bottom of the carb on to the manifold leaving a steaming puddle... what do i need to do to fix this? ( im new to all this im learning ) i got the car for my 16th birthday