This is quite an advanced topic to start. And the truth is, the quality is bad in most of the cases. There is not general guarantee that it will work, because it depends on so many things if a DEM can be generated, error sources are multiple and there is no basic recommendation for the single parameters. You will have to know what you are doing in order to make good choices.
Probably the best topic to learn from a successful example is here: The Order of DEM Creating Steps
But you will have to bring some willingness to learn what these steps mean. This is an excellent collection of useful information: http://www.esa.int/About_Us/ESA_Publications/InSAR_Principles_Guidelines_for_SAR_Interferometry_Processing_and_Interpretation_br_ESA_TM-19