Take a look through the pictures that the link in my signature takes you to.
I posted pictures of the front disk brake job and the rear drum brake job, including replacement of the drum.
I HIGHLY recommend that you get a drum brake "hardware kit", they are cheap....and give you all new springs and clips.....really make the job easier and better.
Also....I originally bought drums from NAPA for about $50....made in China.....
I ended up taking them back because one or both was seriously out of ballance or out of round......made the car shake at anything over 45mph.
I tried rotating tires.....having the tires spin ballanced.....messing with this and that...and solved the problem by putting my old drums back on.
So I returned the NAPA drums and got some Bendix drums from Advance Auto Parts.......
I have since replaced both rear wheel cylinders.....one started to leak....which required replacment.....and I did the other one later just as preventative maintenance.
The big thing that I ran into with the rear wheel cylinders was that the nut that holds the metal brake line to the wheel cylinder was rusted to the brake line....so that the whole brake line wanted to turn as I turned the nut......
I ended up spending a lot of time messing with that......removed the wheel cylinder from the backing plate and spinning it on the brake line to get it off.....and finally got the nut to come free.
Other than that.....wheel cylinder replacement was easy.
I would also bleed the brakes....flushing a lot of new, fresh brake fluid through the system.
Take note that my windstar is much older than yours.....so much more age and wear and tear.
However the pictures should match up to your job.....as long as you have rear drum brakes.