Let's first go into a bit more detail about what we mean by "the profile photo". This is the photo that will be added to your contact card and is part of the information that will be stored when sharing your contact details. You will find it in your profile settings, the menu option in both the mobile and web app.
There are two ways to add or update your profile photo:
In both cases, you should look for the "profile settings" and tap the round circle (this could be empty).