First, make sure you are logged in. Then head to your profile page.
To edit your profile picture
Click the ‘Click here to edit profile picture’ banner on the top left of the page.
To edit your cover photo
Click the 'Click here to change or reposition your cover photo' banner in the top centre of the page.
Then upload your chosen photo and click "Save".
Profile picture dimension
Use this guide to help you choose a profile picture which fits both your public-facing profile and your search page listing.