When on a students profile, on the left you should see a picture template. Underneath this there is an upload button. Click this.
A pop up box will appear to help you upload the photo so click browse. Once you have selected the photo you want from your computer, it should just appear in the picture template.
Change an existing student profile photo
To change an existing profile photo, just repeat the same steps as above. The new picture will just replace the old one without having to remove or delete it.