can anyone just help me out and tell me how to create and append to a zip file using preferably zlib, but if theres somthing better out there I will have a look into it (I would love to use physicsFS, but I'm fairly sure that is just an opener)
zlib only handles the compression aspect of it. The actual .zip file format involves other things like headers for each file, a table of contents, CRCs, etc.
Unless you want to write your own .zip library (quite a bit of work), you're better off using an existing one. AFAIK, PhysicsFS is perfectly capable of both reading and writing zip files.