What do I use to hang backwash up
You mean "backsplash?" What are you using? Tile?
It depends on the material. You can use tile which will require adhesive and grout. There is also stick on backsplash to.
It depends on the material the back splash will be. Different steps for tile or wood or laminate or stainless steel.
Tile requires mortar and anything else will have a different application method. It depends what you're using.