Just to calibrate the circuit, first short the inputs together and adjust the offset potentiometer to obtain 0-mV output from the LM351.Depends on the context. Why are you being instructed to short the inputs together? Shorting the inputs together will not damage anything, but it usually is not a good idea. If this is for some kind of performance/noise test, what is the test?
Also, are you sure they don't mean to short the input to ground?
ak