I had a quick look at my OE settings at home:
Go to the 'Accounts' options, select the account and press the 'properties' button. Now in the dialog go to the 'servers' tab.
Under 'incoming mail' you should have the pop server where your mail account is registered (e.g. pop3.virgin.net). The next box should have the outgoing mail server, select AOL's mailserver (something like smtp.aol.com). Make sure the login details for your mailaccount (virgin.net in this example) are correct. If necessary tick the bottommost box and click on settings to the right to add the login details for your AOL account.
Good luck, hope you get it working!