Double Din Help

[Baggins_]

Right so this is my first post on here so I hope that someone can help me. I have just become the proud owner of a 1998 mk2. At the moment it has the standard, single din, Bose head unit along with a Mini Disc player underneath. Unfortunately neither of these work so I need to replace them.I am looking at installing a Double Din JVC unit. So I have one question, what do I need to install it? Any help would be much appreciated. Cheers