If you mean your Contacts folder, then do the following:
Choose File > Import and Export
Choose "export to a file" and click next
Choose what type of file you want (Excel is good, or CSV -
depends on what you want to use to access the file
afterwards)
(here my instructions are going to get a little
fuzzy, 'cuz I jsut found out I don't have this feature
installed at home...)
Make sure you select the right folder to export (i.e.
Contacts most likely)
Choose where to save the exported file & give it a name.
Click Finish
Good luck!