Once in your Inbox, click on the "Settings" gear icon near the top-right side of the screen.
Select "Forwarding" in the Options menu on the left and check the box for "Enable forwarding" and enter your destination email address. There's also a checkbox for whether you want to keep a copy of forwarded messages in your Office 365 Mailbox.
Click the "Save" button at the top of the page. (Make sure you click SAVE at the top to Save the changes or it won't set up email forwarding.)
Any FUTURE email that comes to the mailbox will be forwarded to the email address you entered.