Header and Source code can be modified into this window or directly from Visual Studio from the solution (or any other text editor).
If code is modified, it will be automatically saved when OK button is depressed.
It is a good idea to save the modified code under another file to keep the original one unchanged. Usebutton for that.
Refer to "Understanding Runtime" in the Tutorial document of vsTASKER.
Do not forget that all provided source code in vsTASKER environment is subject to change from one revision to one another. So, it is a good practice to change the name of any cpp wrapper if any change must be applied on it.