I'm also new, but I was unable to upload a picture or edit my profile in my phone. I got an error message when attempting to edit my profile. If you do figure out a way let me know!
Thanks. To OP, so sorry to hijack your thread. To show how sorry I am I will leave you with the steps.
1. Request desktop site
2. Click on settings
3.Click on edit avatar under my profile
4. Select customize and upload
Note: I uploaded from documents rather than camera so I could select from my gallery.
You can also update your profile by clicking edit profile.