You need to click on your blank profile picture to the top right , between the POST button and the burger menu , and click SETTINGS , or just click here :D https://steemit.com/@phantomlegacy/settings
you can paste a public link .. not upload directly . If you want to upload your own pic I suggest IMGUR https://imgur.com/upload to upload the picture, then you copy the link and paste in "profile picture URL" :)