you can download a program called winace, just searsh for it on google and it'll come up. that allows you to compress your files, but it does mean whoever is downloading it needs some similar software to de-compress it.
Don't listen to the tarranjoe, he's talking about compressing files, not audio files. Zipping an audio file will not really change its size.
I assume you recorded the mix as a wave file. Compress it to .mp3 or .ogg or .wma using any audio conversion program. If you recorded to .mp3 and have a huge file it means you set up the compression options improperly - 128kps or 192kps is fine. You can get good quality for 1 mb per minute.