How do I begin to develop and follow correspondence emails from Cases module within sugar?

So I just synced my outlook account to Sugar so that I can start to sync our customer inquires to the "cases" module. When an email comes in I choose "new sugar record" and "cases" from the drop down and the email is loaded into the cases module. However, when I respond to the email from Outlook the follow up email is not recognized in Sugar. Where and how do I correspond so that I have a record of correspondence with each case file? Is it done from the Cases module or somewhere else? Note: I am extremely new and novice to Sugar. We are running Sugar Professional 7.5.2.1