Can any one tell me how i can get a kind of border at the bottom of my ui with fps, latency and so on ? also one that can act as a background for my action bars (using bartender3).
Also TitanBar or FuBar, although I'm not sure if FuBar is updated anymore or at least at the moment. FuBar is also almost fully modular, i.e. you have to get all the fu_whatever sub-addons installed to be able to display whatever it is you want to display. I recommend TitanBar, personally, but the difference is marginal and mostly graphical.
bar at the bottom of the screen with fps and stuff like that is a few variations, all doing the same thing though. You have TitanPanel, Bazooka, ChocolateBar, FuBar(if it's been picked up again). can do something like it with StatBlockCore, and LibDataBroker.
As for the background for action bar, not really a background but ButtonFacade will give a nice border to your action bar buttons. The Addon itself includes 3 options, but you can find more on curse.com or wowinterface.com that will other options. There is also kgpanels, that will backgrounds to various parts of the UI.
kgPanels can be used to provide a background/bar image for anything. For the information, I suggest a DataBroker display addon (Bazooka, ChocolateBar, StatBlockCore, Fortress, NinjaPanel) using LibDataBroker (aka LDB or Databroker) plugins.
I use Sunn-Art personally for the back ground. It still glitches water effects when they are turned up and in DX11 mode having re-sized the view point. Also as suggested before Button Facade is pretty cool for customising your buttons. I prefer the simpler look myself though.