Will Penn station take me to Boston ( Fenway stadium) how long? What train do I take? Thank you.

You may take Amtrak, but it will be costly upward to 240 dollars The travel by train less than the bus. However, at a longer time the bus from NYC is much less under $40, one way. Please check both the Amtrak and gobus.com sites. https://www.gobuses.com/

You could take Amtrak