How do I access the node editor for a Megascans material I imported using bridge?

[MisaelChan]

I double click on the material and an editor window appears but not the “node” editor.

[ClockworkOcean]

This is a material instance. If you scroll down further you will see the main material. Double click it to open.

( You might come across another material instance first, you keep following through until you get there ).

[fomiA30]

See it is still not showing me node editor, instead when I double click to open the material, it show the 2nd window, where I hit hierarchy to show me node tree, it shows parent material which is absolutely different, and I still clueless to find it. I am beginner, please help