First of all the Red Light District has no ticket since it's referred to an area/zone if you will. It has no entrance fee.
Secondly, it is a prostitution district (obviously) and yeah you see women on displays - so if your morals, values and faith boundaries don't allow you to go there, don't.
But,
I'd say go if you get a chance, it's one of the most eye-opening experiences, the feeling of women selling themselves all around you is a very powerful and heart wrenching feeling. It's one thing to read about this stuff and entirely another to see it infront of you and particularly in the Amterdamned manner. SO yeah.