Interesting question but perhaps not suitable as there is not one right answer.
Contextual to the control
You invented a concept with many new controls, like a button that looks like a door or a painting. It looks great and may be great to use when learnt, but unlike standard gui controls, it is not obvious what is clickable, dragable, openable, editable, and so on. So users will have to analyze each and every one of them, trying to figure out how it functions. This is what you want to help them with.
As @Benny Skogberg suggests, a contextual help is needed. I would like to point out that the context here is not only each screen as a whole but the controls themselves.
In Google's iPhone app they have a contextual help question mark button:
- It opens an overlay help-board, where each control had a question mark button on top of it.
- Clicking a control help board each control has its own contextual help text.
I think this is what your app needs.
I implemented this myself for an RIA a year ago. It is quite easy to make a system where you just specify the coordinates for buttons and texts, for each control. Now, a year later, the design has changed so much that it has to be redone. So if you do it, make sure to schedule time in the end of every release to adjust this overlay.