Each email that is sent to you (after people submit their picks from the Web Entry Form), at the bottom of the email, in light-gray text is:
OfficePool Managers, Select & Copy the following for import:
followed by some more data. You can either select the entire contents of the email and COPY that (Edit->Copy menu item) OR you can select the light-gray text and copy that.
Once copied, you would then PASTE (Edit->Paste menu item) that into the field (below the text "Copy SOURCE of the Email and Paste it into the field below")