How do you attatch the ribbon on the cake? Does it get greasy?

Yes ribbon will absorb the grease from buttercream. You can cut some parchment or waxed paper the size of the ribbon and place behind it. I attach with melted chocolate.

The ribbon can absorb the grease from the buttercream staining your ribbon. Like previous poster said, use parchment or waxed paper. I use parchment paper with my ribbon so the paper hits against the cake.

The ribbon will absorb the grease, but if you pre-grease your ribbon by rubbing a little Crisco on the back of the ribbon you will not have the grease spots. It will darken your ribbon slightly but doing it this way will avoid the chance of getting grease spots on it because you have already greased the entire ribbon. I have done this many times with ribbons on my cakes.

You can put scotch tape on the back of the ribbon and it will protect it from the grease.

I use packaging tape on the back of the ribbon then attached it with a little royal icing. Works great!