How do I put all of my emails both old backed up ones and new ones coming in, onto my Outlook on my Mac laptop? I have this set up properly onto my mac desktop, but how do I get my old emails from my Outlook on my mac desktop to also appear on my mac laptop when I open up Outlook?

I have no issues receiving and sending out new emails since I made the switch to office 365 but I just can't figure out a way to transfer the old backed up emails onto the laptop Outlook.

Please help me!! Thanks :)

Joanna