As posted in our latest iPaaS Puzzle:
There is a great free webMethods.io Integration Introduction Course available in Software AG’s Learning Portal with a chapter on Creating Rest Connectors!
Let it run in one window and create the UN connector in another using the UN API Resource Page as the source for your connector.
I don’t think I have it all right yet, but I first got stomped here when I came to this step and wondered why my Add button was greyed out.
When on the lecture side the Add button is deep blue:
Once you see it, it is easy. 
