To change any template, choose "Edit" icon.
Then you will see the editing view of the questionnaire and by selecting "General information about the questionnaire" you can design the header of the questionnaire.
Adding pictures select "Picture" icon and to add a link select "Link" icon.
Same adding option applies to every question group header and to any separate question.
The default setup for the general information picture in the questionnaire's view is that it will appear on top of the questionnaire as seen on the picture below with 360 degrees.
The pictures within the questions will appear before the question and here is added additional link for the picture that will open in another tab.