Greetings,
You would first need to save it to your documents folder, and then compress it with whatever compression program you need to use. ZIP is the default format, so if you want, say, .RAR or something else, you would need to get that program.
Otherwise you could use the command line and .tar it. The are all kinds of ways, but directly from pages to email it will be.zip, as far as I can tell.
Cheers,
M.
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