You could get down at PRAGATI MAIDAN to reach NZM from NDLS. board the metro from NDLS (yellow line) and get down at rajiv chowk . from there board the Blue line ( the train going towards vaishali/noida city centre) and get down at pragati maidan .
you would be able to use metro to reach NDLS AS NZm will be soon be operational as a station(almost 2(max) years later) being a aprt of Phase 3 of Delhi metro.:)