Need to get to Newark airport with
 

my young child from the EAst 20's Manhattan. Not doing taxi. Any ideas on the bus, train? clueless. tia

The Newark Airport website has ground transportation info.

panynj.gov/CommutingTravel/airports/html/ewr_transportation.html

Take NJ Transit from Penn Station to the Newark train station and connect to the AirTrain; the connections are fairly painless. Penn Station is pretty much just across town: basically 7th Ave between 31-33rd Streets. I would highly recommend a taxi to Penn, but you could always take a crosstown city bus (mta.info -> Maps -> Manhattan Bus for details).

Just to clarify. The station you're getting of the NJTransit train is called "Newark Int'l Airport". It is on both the Northeast Corridor Line and the New Jersey Coast Line, so many trains heading towards Trenton or Bay Head will stop there. [But not all, many trains also skip that stop, so check the timetable carefully.]

Your other option is to take the Lexington Avenue subway (or cab for a few $ more) to Grand Central and take the shuttle bus from there. It may cost slightly more than the train option - but will be easier - with fewer changes - if the child is small and/or you have more than one bag.