insect enzyme assay protocol

Hi, I want to do an enzyme activity assay for the enzyme NADH Cytochrome C reductase of an insect. I checked for protocols which were over my head as am a basic physics student. If anyone can help me with the protocol methodology, and other basics please.

Also some of the protocols which i referred talk about the mitochondria instead of the enzyme of interest.
Please help me on this asap.

Thank you