Making a program just with api

HEHE...... sorry but I still know so little about API, and still got much to learn.

Okay.... i know how to make buttons and forms with just API, but what I want to know.... is how can you make a command for it, like, if they click the button..... APIs doesn't have stuff like "Command1_Click", "Text1_Change" etc.. How would you make one in API?

If you can't explain, any codes would be good enough..... or both should be perfect..... If none of the above then, "WHERE ARE THE API GURUs!?!?! HELP ME OUT!"

Thank you.

You have to use subclassing.
Here is what I got by searching for Subclassing here on vbWorld.