@abr88
Never be shy about not knowing things. We all started out that way and some of us have still a long way to go:Blushing:
In addition to the excellent advice given already, one quick and easy way to determine whether your account(s) is POP3 or IMAP is to:
On your iMac, Open Mail, then go into Mail Preferences - the easiest way to do this is to hold down the Command key and whilst doing so, tap on the Comma key (Cmd plus ,) or you can Click on Mail on the top menu bar, then choose Preferences from the drop down list.
Once done, Click on accounts - as in the screenshot below. On the left you will see your accounts and underneath each will be the the word POP or IMAP. In my case, both show IMAP.
That's a reasonable starting point. This advice should be seen as additional to that already given.
Ian