Once logged in you can access the menu by tapping the profile icon(desktop) or the hamburger menu on mobile.
From this menu, you can tap > EDIT PROFILE

You'll be presented with several tabs to choose from, allowing you to change the profile image and banner, as well as edit the bio information and add an intro video which will be located towards the bottom of this page.
To update the Profile photo and Banner just click the profile photo to prompt and upload, and for banner tap the "edit cover" button.
Once you have made your desired changes, scroll to the bottom and click the "Save Changes" button.