I can tell you the steps but you will have to read a bit to understand what is going on there and how the parameters and scene characteristics influence your results. ESA has compiled very good documents for this: http://www.esa.int/About_Us/ESA_Publications/InSAR_Principles_Guidelines_for_SAR_Interferometry_Processing_and_Interpretation_br_ESA_TM-19
This is also a nice tutorial but it refers to an old version of SNAP and many things changed in the meanwhile: https://saredu.dlr.de/unit/insar_deformation
- coregister the images
- create inferferogram and coherence
- subtract topographic phase
- optionally multi-look or filter the interferogram
- unwrap the interferogram
- convert unwrapped interferogram to displacement