To add your picture to your Office 365 profile, follow these steps:
1. Go to the Myapps dashboard and click on the profile icon in the top right corner and click on "View Account"
2. Click on your initials or picture above your name and it will have you change your photo.
3. Click on "Add a photo", go to the location of the photo you want to be added, and click Open. Once the photo replaces the current image, click Save.
Your new profile picture should now be visible in Office 365. Note that it may take some time for the picture to propagate across all Office 365 services.