For example, i need my own compress format (like zlib). I need to standard archivers this Compress file does not open! What should I do? Can I do this with the help of zlib? Or slightly altering zlib? Or will have to write your compressor and decompressor?

I hope I explained understandable. Sorry for my English

I hope you know a lot of math. Writing a compression schemata is not a trivial task.

You could just use a standard compression library (like zlib) and store the resulting data in a different file format than normal.

Good luck!