I am following this blog,
and have all the commands in my script except the one on the right with the kangaroo symbol.
Can anybody tell me how I can get this command/what it is called with the current version of kangaroo? Any help would be much appreciated, thank you.
that’s the Solver component… ie-- pretty much THE main component of Kangaroo 
I am fairly new to this, how does the current command compare/translate with the old one? 
There are alot of kangaroo 2 examples provided by Daniel. You should open them, they come with the download from food4rhino and there are many more here: https://www.grasshopper3d.com/group/kangaroo/page/kangaroo2-additional-examples