cart total in header, how to php echo?

I am working on adding a fixed header for mobile device that shows a cart total price(no text displaying number of products) and a button for "go to checkout".

Was thinking this would be pretty easy but is stuck on pulling the cart total into my "mobile header" code.
I was thinking it would just be to write but that returns an error.
Im no php guru so would like some help with this

Found an similare problem in an old thread but that was for OC 1.5.. I run 2.3

Im planning on adding this header in the header.tpl
Do I need to mess with the controllers or what?

Thx guys

Yes, you need to add a foreach clause in header controller to get the "total" order total and then assign it's value to some distinct variable.

ok, thx. One step closer

Could someone help me or point me in the right direction regarding what I need to do in the controller and how to later pull the price in the header.tpl?