How can I identify the poles of the magnets?

There are several simple methods that can be used to identify the (Scientific) North and South poles of neodymium magnets.
1) 
The easiest way is to use another magnet that is already marked. The
North pole of the marked magnet will be attracted to the South pole of
the unmarked magnet.
2)  If you take an even number of magnets and
pinch a string in the middle of the stack and dangle the magnets so they
can freely rotate on the string, the North pole of the magnets will
eventually settle pointing North. This actually contradicts the
“opposites attract” rule of magnetism, but the naming convention of the
poles is a carry over from the old days when the poles were called the
“North-seeking” and “South-seeking” poles.  These were shortened over
time to the “North” and “South” poles that we know them as.

3)  If you have a compass handy, the end of the needle that
normally points North will be attracted to the South pole of the neodymium magnet.