Why not put a "Help" button on your forms. If your user needs it, they click the button, and it opens the help form.
It would be fairly simple to give the users the option to turn off/on ALL of the help windows using a global booleanvariable. There could be a "Show Help" button on your main menu, and if the user clicks that, it toggles the variable.
Test that variable before opening any of the popup windows.
If you want the users to be able to choose which windows will pop up, you'd probably have to build a user profile table with all of the user names, pop up names, and a yes/no column to indicate whether or not they want to see that pop up. The values in the table would have to be tested before each pop up is opened.
Inspiration Through Fermentation