POP to IMAP

My e-mail server provider, Verizon, was recently bought by AOL. This change allows POP accounts to be converted to IMAP. Would anyone recommend a concise description on how to change the type of an existing email account in Mail from POP to IMAP?

Do I need to contact AOL first to switch something, or this is something I should be able to handlein Mail/Preferences/Accounts?