If I use satin ribbon and wax it with wax paper first does it change the color of the ribbon..or any suggestions? I dont decorate cakes i am only adding this to the cake after it is made.

It shouldn't change the ribbon since the wax paper is on the back side against the cake.

I am talking about doing the ironing of the wax paper to the ribbon..not the method of cutting it and putting it behind it.

please explain what you are talking about when you

Are you putting the wax from the wax paper on the ribbon so the grease from the buttercream won't soak into the ribbon? If you put the ribbon on the cake and the grease soaks into the ribbon and it will it will soak the whole ribbon and not be noticeable. this was my daughters wedding cake and I put the ribbon around it very late the night before yes the grease soaked the ribbon but you could not tell
http://www.cakecentral.com/cake-photo_1064983.html

Jibbies

I just put ribbon on a wedding cake yesterday and I backed the ribbon with contact paper, didn't change at all.

I have backed satin ribbon with clear packing tape. No Problem, no leakage.

See one with black ribbon below:
http://www.cakecentral.com/modules.php?name=gallery&file=displayimage&pid=1123023