Import outlook files to thunderbird

Help article recommends installing installing version 31.8 of thunderbird and importing outlook files using that, then upgrade to the more recent version of thunderbird. However having installed 31.8 when I try to import the pst files, I'm told that thunderbird can't find mail to import. There appears to be no option to browse for the files. My outlook files are in the usual folder - documents/outlook files but thunderbird can't find them.
I'm trying to import historical emails and haven't set up an email account yet in thunderbird. Would it make a difference if I set up the account then tried to import old emails or would something elase make a difference. Any ideas would be very welcome.

Hi, Help article recommends installing installing version 31.8 of thunderbird and importing outlook files using that, then upgrade to the more recent version of thunderbird. However having installed 31.8 when I try to import the pst files, I'm told that thunderbird can't find mail to import. There appears to be no option to browse for the files. My outlook files are in the usual folder - documents/outlook files but thunderbird can't find them. I'm trying to import historical emails and haven't set up an email account yet in thunderbird. Would it make a difference if I set up the account then tried to import old emails or would something elase make a difference. Any ideas would be very welcome. Regards Steve