Ladies,
I have a pelvic floor disorder, diagnosed after miscarrying my first child 
My question is that I have been prescribed physical therapy. How in the world does this work? My first appointment is on Friday and I just want to be prepared.
Your therapist will start by taking a history of your pain, gynecological and voiding/incontinence history, etc. Then they will start with a basic musculoskeletal exam: posture, flexibility, strength, etc. An internal exam may or may not be done on the first visit also to assess strength of the pelvic floor. A special device may be used that takes a digital readout of your ability to contract the pelvic floor.
Based on that, your therapist will design a treatment program and/or provide advice. It may include behavioral modification of urinating, exercises for the pelvic floor and/or the legs/back, and sometimes stimulation and/or biofeedback to the pelvic floor musculature, etc.
Best wishes.