Dipee65's method will export your whole Address Book, not just the relevant group.
The only way I know to do what you want is to create a copy of your address book, edit it so that only the single group is left and then e-mail the result to the Chairman and Secretary.
To do this, follow Dipee65's instructions and export your address book file to the desktop, giving it a name such as 'Members'.
Double-click on the file Members.wab, which will appear on your desktop. Edit this copy of your your address book (by deleting unnecessary contacts), so that only the group containing club members remains. (Remember, you're only editing a copy of your address book. The original one, in Outlook Express, will remain unaffected by any changes you make).
Then e-mail Club.wab to the Chairman and Secretary, asking that they use the 'Import Address Book' menu item within Outlook Express.
Chris