From a PC/Laptop/Surface, open MS Outlook.

Select FILE (top left)

Click on AUTOMATIC REPLIES button

Check the box "send automatic replies" and enter your INTERNAL out of office message.

Click on the "Outside My Organization" tab and enter your EXTERNAL out of office message.  Note that the person emailing you will only receive the Out of Office message ONCE.  This means that if you are out for a week and they email you on Monday and receive the Out of Office message, they will NOT receive it again if they email you on Thursday.  This is not within Bartlett's control.  

When done, press OK and the back arrow (top left) to exit.  

To remove the Out of Office upon return, you will be prompted every time you sign into Outlook (top right corner).  

**  Note:  Do not setup RULES here.  There is a separate article title "Setting up Email Forwarding".