Here's how to add a Cover Image to your steemit!
So heres, how to add one to your own profile!
First get yourself a image that you would like, to have appear as your cover photo. Keep in mind, that steemit will pick the center of the image to crop out, for the picture.
Alright i'll chose this one.
When finished, go over to http://postimages.org | We are going to use this as upload tool since steemit only takes Url's.
Make sure your page looks like this : Do not resize my image and No expiration.
Go ahead and upload your image and you'll see this. Go ahead and copy the DIRECT LINK.
Once done go back over to steemit and go to you settings, its right next to your wallet page. And where it says : COVER IMAGE URL, go ahead and paste your url you got from http://postimg.org | Next click UPDATE and it should appear on your profile page, a brand new cover image to make your profile look even cooler!
I hope this helped you out.