Who is your email account provider? Is the account tied to Incredimail? (I don't know much about Incredimail.)

If you have a regular POP or IMAP connected account then you can set it up in any email client, including Thunderbird. However, given that there has been a steady trickle of frustrated users over the years trying to get messages out of Incredimail, I would guess that it uses POP so the only copies of your messages are there on your computer in whatever arcane format the Incredimail client uses.

So, I think you may be able to run your account using Thunderbird. I am not so confident that you'll be able to preserve all your old messages that are currently in Incredimail.

You could get a new account, set it up in Thunderbird, start using it and gradually, as need arises, switch all your correspondents over to using the new address.

What I need is to get My incredi mail address to thunderbird I use gmail as My address but all My contacts are in incredimail address book I haven't got the paitence to hand type all into new program There should be a import thing some where

Export addresses from Incredimail as a csv file, and import it to TB:

http://kb.mozillazine.org/Importing_from_Incredimail

http://kb.mozillazine.org/Import_address_list_from_text_file

This operation usually works better if you edit the csv file in a spreadsheet or csv editor to make it more compatible with the TB address book structure.