Blogger tips from their Help pages

Blogger "help" says:

To create a "team blog":

"To add authors/contributors, ype the email addresses of the people you're inviting to the blog, separating each address with a comma. They'll receive an email with a confirmation link soon. Note that they must have Google Accounts, and if they don't already, they'll be prompted to create one."

If you are having trouble with your invitation: 

If you receive error messages when trying to accept an invitation to a blog, please try the following suggestions:

• Get a new invitation. A Blogger invitation link will only work once, so if it has already been clicked on, you will need to get a new invitation from the administrator of the blog.
• Restart your browser. Log out of Blogger, then close all your browser windows. Open a new one and try the invitation again.
• Copy and paste the link, instead of clicking it. Many web-based email services (e.g. Hotmail, Yahoo!, etc.) cause problems with the way they modify links to display them on their own sites. If this is the case, you'll need to copy and paste the link into its own browser window in order to use it.
• Have the invitation sent to a different address. You can accept an invitation from any account, or create a new account with any email address, regardless of which address was used to send the invitation. So if one address doesn't work, try another one.
• If the invitation is more than a month old. Request a new one.