You will need a Google account (not necessarily a Gmail account) and be a member of the MWBS Updates group in order to edit the Wiki.

If you are interested in editing the Wiki, scroll to the bottom and look for a link to 'Sign in' on the left of the row of text. Click that, input your relevant Google account credentials, and you should be good to go! The spreadsheets should be editable by opening them from within the wiki, or from your Google Docs account.