It looks like you don't have the correct files in place for the control panel, because you should see a white and blue UI. From your v7.6.0 install archive please make sure that you're using the same files in the /styles/admin.css, /admin, /languages/english/admin, and the /templates/admin folders.
Edit: Looks like it might just be the missing /admin.css file, but just wanted to make sure you updated the others if you left them out for some reason.