Are you a DirectAdmin administrator? If so, then you don't have to do anything; DirectAdmin sets up mailboxes to use both IMAP and POP.
If you're an end user, then what do you need to know? If you set up your local mail client to use IMAP it will just work.
If you need to learn how to set up your local mail client to use IMAP, well, that's beyond the scope of the DirectAdmi forums.
Jeff