Login at the administration page of the blog: http://blog.stud.uni-goettingen.de/deinblogname/wp-admin.
At the menu item “Headers”, click on “Add New File”.
Click on “Datei auswählen” (“choose file”), choose the photo you would like to use and confirm by clicking on “Upload”.
Switch to the menu item “Settings” and choose the uploaded photo.
To be displayed correctly, the photo should have the size 260×120. You can download a template here. Positioning the background-transparent profile picture in the middle of the template creates a very nice effect. If you have any problems while editing your profile picture, you can also send the image to firstname.lastname@example.org for editing. We will try to respond to these kinds of requests as quick as possible.