email from Thunderbird import issues on a MacBook

Thunderbird (an email program from Mozzila) has a version that installs (and works) on a MacBook Air. Thunderbird also has an import feature, however I can not make this work.

Has anyone ever managed to import the settings and email from a PC to an MacBook Air? Where can I copy a working folder from my PC to my new MacBook Air so that the Thunderbird import feature can find it. Conversely, can one copy the folder "someplace" and do a fresh install of Thunderbird and everything works.. like it does in Windows.

Be very grateful if anyone could help.

Thank you for your time