add login to header just like www.ads-software.com

Is it possible to integrate the login box near the top of my themes header?

I use the arras theme. And I love how www.ads-software.com has integrated this into their header. I know it would be somewhat complicated.

I want it to say “Sign in” or “Register” and display a sign in box.

How would i go about doing this?

Many thanks,

This is my webpage, i’d like to add the same exact fields and links that www.ads-software.com has above

https://www.badcompanytwo.com