To change the profile picture on your diary, you can go to your diary profile by clicking on the main menu and then clicking Profile.
Once you are at your profile, click on the Settings dropdown:
On that menu, click on Change Profile Photo. This will bring you to a screen that is titled Change Avatar.
On this screen, you can click the Select your File button to pick an image from your computer, or you can click on the Take Photo tab which will allow you to take a picture with your computer or phone’s camera.
To delete the image that you are using, click on the Delete tab.