You can add or update your profile picture in Planday either from your browser or on the mobile apps.
From your Browser
Select your name at the top right, then Edit from the dropdown menu.
Go to Misc > Picture, and select Edit
Upload your photo, and Save.
On the Mobile app
Select Account at the bottom right of the screen.
Select Edit profile.
Select Edit Photo in the centre of the screen.
Take a new picture or upload a photo, and Save.