How do I get from 8th st port authority to 911 museum?

The Two trains

Take the E train to World Trade Center. It is the last stop on the E Train.

Found this on another site: If you're talking about Port Authority bus terminal you need to go to the A C E subway line and then head downtown. It'll probably say Brooklyn but get on the E train and it takes you right down to the World Trade Center and that's where you'll find the museum. If you get on the A or C train you will have to transfer to get on the E train. So make sure you wait for the train marked E.

The 1 train or the 2 train