Microsoft provides extensive documentation on how to configure various e-mail programs using IMAP or POP to access your Office 365 account: http://help.outlook.com/en-us/140/cc875899.aspx .
This web site is excellent and will answer virtually all the questions you may have, but we can provide a few additional tips to help you successfully configure your e-mail program to access your Office 365 account.
When configuring an e-mail client to your Office 365 mailbox you will be asked for a User Name or Logon ID and password. The User Name is your JHEDID@JH.EDU and jhed password.
For example if your Johns Hopkins JHEDID is jsmith99, your Office 365 User Name is firstname.lastname@example.org.
Here is an example of an E-mail client connecting with IMAP: