How to start a court hearing if mother is disobeying a court order to see her son?

I was told to get a lawyer or go online to start these proceedings. Ok we have 50/50 custody pay $185 a month in support. she goes to school everyday she is ordered to have him and most days she doesnt even take him... MY QUESTION is how do i start to proceeding to go on forward to HOLD HER in contempt for disobeying a court custody order?