Create button in header

Good evening,
I want to create a button in the header in the upper right corner. (see picture). In the mobile version it should be visible in the middle below the small menu and logo/buger menu. At this moment a telephone number is publicated but in stead of that should be the banner/button.

I tried to create a widget area but this occurred to low.

Could you provide step by step how to manage this?

Thanks in advance, Bert