How to fix wrapper(Menü)on the upper screen border

I'm trying to fix the top wrapper on top of the screen. (Example: docs.joomlabamboo.com/ . So far, unfortunately, unsuccessful.
Can anyone help?

Hi
if you want to have a fixed navigation you can use my module Maximenu CK which have an option to fix it at the top of the page
CEd

Hallo ced1870
In the wrapper are several blocks, logo, text, search and the menu.
The site is still local, but I will create an access in the next days.
Any idee to fix the wrapper?

if you need specific assistance, please use the support contact form available with your membership