There are many ways to learn to code these days. From coding bootcamps like Flatiron School to online courses to totally free beginner resources. The best way to learn to code depends on many factors, but the most important one is you. See what course is best for you.
Your applications are not supposed to be able to interact with the secured desktop at all.
Why do you need to get a screen capture of that desktop? Perhaps we can help you find a different method to achieve the same end result.