When I was first looking into how to get started with using the ETABS api for making my own addins I found no easy examples out there. I thought I would simplify this process for you.
Simply follow the steps below to get started. I chose Dynamo since it is an easy way to "call" these methods.
Also you could reference the API docs that are installed in your ETABS install directory although they will not be as easy to understand as the example above.
Have questions? There is a dynamo package that has all the API methods exposed called "Simplex"
Don't know about Dynamo? Learn about it here. https://dynamobim.org/
Also Simplex comments post here. https://github.com/marcellosgamb/SIMPLEX