Perhaps my quetion wasn't clear. I could set up Thunderbird but ccouldn't get AOL to send messages from AOL using Thunderbird.
Ivestigating further I find that this seems to be a problem with AOL.
I have deleted Thunderbird reinstated Microsoft Outlook Express and use my hotmail address to send mail,using AOL as my ISP.
Again I can't send mail from 'M.O.Express'if I want to use my AOL addres,seems AOL want to block it!
Anything is better than all the bumf that comes with AOL, so I'll carry on using hotmail,