Welcome :)

How to add profile/background pic - also how to comment with pictures :

1. make a post with the image that you want as profile pic/background pic.
2. go to the post and right click on the image, then choose 'copy image location'
3. go to 'profile settings' and paste the link in your 'profile pic/ background pic' space.
4. enjoy :)

Good Luck on Steemit!