As the help author you don't need to do anything special to create normal context-sensitive topics. They are simply normal TOC topics and normal popup topics. They become "context-sensitive" when they are called directly from the application. What makes field-level popup topics a little different is the fact that they are called on their own, without the help viewer, but when the same popup topics are called within the help they behave the same as other popup topics. The difference is in the way the topics are called, not in the way they are created.
For more background information see the Context-Sensitive Help & Popups chapter in the Reference section.