Hey, If you search around here you should find some useful links.
Your basic workflow is to get References from the Element and define a line for the dimension location.
This can be quite tricky. I know that @Alban_de_Chasteigner is expanding his Genius Loci package to expand this functionality. I’d get the latest version and have a play.
Here’s one of my graphs, but as I say, I would probably use some of Alban’s nodes if I was to do it again 
I’m not sure there are any nodes for angular dimensions, but there is a method in the api…
Create Method so it is possible and the method looks similar to the other creation methods.
Good luck
Mark