Where to put CSS /Code for Tabs
 

Trying to add some tabs flush right over and to the right of this:

https://vborg.vbsupport.ru/external/2009/02/37.png

Where exactly would I put my html/css for it?

I'd put the css in the head and the html in the navbar (if that is where the login code is). That box is normally a table, so just add your own div or table above it.

You may also have to transform the navbar away from tables, as some things might act weird when you try to position tabs above it.