Gmail will not work with Thunderbird

In Thunderbird's account settings, I select account actions, then "Add mail account". After entering the requested info for my Gmail account and select "Done", a large Google window pops up saying "One Account - All of Google". At this point, I seem to get stuck in a loop that repeatably asks for my email address or phone number. Apparently it's a verification of my login on Gmail. I cannot get beyond this and when i cancel, I get a yellow message bar in Thunderbird stating I have an incorrect user name and/or password. How can I get this resolved? Thanks for any help you can provide. - D. Puls