No example of attaching html forms. The engine won't do a lot for you: basically you have a formKey (on usertask and startevent) and thats where you can set a string value. That value should be used to look up the html in your system and display it.
That's completely up to you. It can be something like /path/to/my/file.html. Or whatever you like, the engine does not care. All the engine does is provide the formKey lookup for you. How you handle it and submit variables back to the engine that's up to you.
Can I have any sample example for the same. I've defined the formkey in the usertask,but not able to get the key and throw the corresponding AngularJs/html page.