For some reason when I add fondant onto my cakes, the top of the sides of the cake you can see through ( the fondant is thin ) only the top of the side is thin, I did apply butter cream first to the cake but I did not put too much butter cream, I did use the large Wilton rings on my rolling pin to have the right texture on for my fondant. I also try rolling the fondant thicker and it's the same.
HELP PLEASE!!!!!

It sounds like the fondant is pulling as you cover the cake. I place my fondant on the cake, quickly smooth the top, then quickly adhere the top edge before moving on to the sides. Adhering it in that order keeps the weight of all the fondant from pulling downwards and tearing.

Thanks I'll try it that way next time to see if it works.
I would smooth the top first then smooth downwards on the sides to try and get the air out

Try not to smooth downwards very much. I know it can be tough when you want all the air out, but do it as little as possible. Smooth around, rather than down. Good luck!

Careful smoothing side-to-side too, it can cause wrinkles!!

To avoid pulling I pretend every cake has four corners. I smooth one pieces, then a piece om the opposite side, then 90 degrees away, then the opposite of that. I end up with four sections. What this does is it forces you to not pull your wrinkles to the side so they bunch in one area, and adheres the fondant in 4 places to take some of the heaviness away and stop the pulling. After I do this I smooth it very well on top. Pull out each side section gently and smooth down with your hand first...very gently. Gently will avoid tearing and also fingerprints. After all is adhered you can smooth down and side-to-side without any bunching.