I'm going to be making a cake with butter cream icing, and i want to do the zebra striped look, but i've never used fondant or put it on a cake before. How do i go about applying the stripes to the buttercream cake so it will stay on the cake?
You have to crumb coat the cake first. This will act as the glue for the fondant to stick to the cake. I would roll out white for the cake and then apply your cut fondant stripes on top of the white. I use a craft paint brush to apply water to the back of the fondant decoration. Since it is mostly sugar, the water 'melts' the surface of the fondant so that you can stick it on top of your wrapped cake. Don't use too much water or just dab with a paper towel otherwise you may end up with runs. The goal here to to make it tacky not soaking wet.
Also, if you are going to use black...you may be better off buying black fondant from the store. Black is almost an impossible color to make. Otherwise, if you can make your own chocolate MMF and then color that black...its is easier to get brown to black than white to black.
Do you want a BC coating with just fondant stripes? I've done this before. Should not be a problem getting the stripes to stick to the BC. You can try to lay your stripes directly on the BC. Depending on your crust and your recipe they may stick without any "glue". If you need some kind of glue you can use water or gum glue - use very sparingly or you will have a sticky, slippery mess. Just brush a little on the back of the fondant and put on the cake. BTW, once the fondant is on the BC don't reposition it. Some of the color from the fondant will be on the BC, if you move the fondant you'll have a little black color on that spot.