This should give your posting a bump. I dont use Wanadoo (mines NTL broadband) but your email settings for thunderbird should be the same as you already use for your other email program.
For a start you need your user name and password info. For the incoming email mine is pop.ntlworld.com and outgoing mail server is smtp.ntlworld.com. Using Windows XP you then click on START button then on SET PROGRAM ACCESS & DEFAULTS. From Custom settings place a click in allow mail access for Mozilla Thunderbird if its not already ticked. Perhaps somebody using Thunderbird and your ISP will come up with correct settings for you.