Bad battery or generator. Measure the battery voltage and holler back with what you find.

The battery is new it reads 12.6 volts until you start cranking then it drops to 6.1 volts but all the car does is click or crank slow

At 12.6 volts the battery should be fully charged. 6.1 volts is way too low during cranking. The most likely cause is bad connections at the battery cables. I'll bet you put the meter probes on the cable clamps. Put them right on the battery posts and measure the voltage again during cranking. If the voltage stays high there, clean those connections.