I want an HTML block and the sidebar to stay fixed while scrolling down — can someone help me with that?

Help all icons are invisible on the whole admin area
what is wrong

I plan to make a total backup of the whole script is it enough to do a SQL export and a backup of the server? and if so should I be concerned about the chmod permissions of folders or files?, and if so which files or folders should I give permissions Regards Douwe.thanks in advance