To create a Profile Banner on TeacherSherpa you can use the long yellow rectangle in the Geometry Clipart Collection. It will provide you the perfect size to create a banner over it when you stretch it to touch both sides of the white canvas area.
Once you are done. SAVE your work, click PRINT, and save to pdf.
Once save to your desktop, open the pdf in your desktop and export it to png.
Once you have a png file you can upload it to your Profile Banner section. Just Click Browse, find the png file, crop and size to your specifications and click UPDATE.