Manually Rooting with AOSP this is my first post here. I hope there is someone to answer my question. 
First, I want to understand Android OS better not just copy some files and be finished. 

I am attempting to root my Nexus 6 beginning with compiling Android for it. I was able to compile and upload all necessary images. Now I would like to root the AOSP configuration for shamu. 

Currently I am able to access ADB root by replacing the boot.img with root access but how do I do a proper Android Root and not ADB root. 

SuperSu: How to install it properly from ADB for Nexus 6 and which version!

Thanks in advance!
Generally speaking, you want the appropriate su binary to be executable from the PATH, such as putting it in /system/xbin.  What version you use is up to you, but if you're using SuperSU then use the binary that comes in its flash package (https://download.chainfire.eu/396/supersu/).