The command references for ASR 9K (IOS XR) can be found here:
IOS XR are quite different compared to traditional IOS or IOS XE. If you've never worked with IOS XR before, I'd highly suggest that you download the IOS XRv router OVA image and then deploy it under some sort of virtualization software. You can download IOS XRv here: https://upload.cisco.com/cgi-bin/swc/fileexg/main.cgi?CONTYPES=Cisco-IOS-XRv. Even though it's not the traditional Cisco download site, you should still be able to access it with your CCO login.