This folder containing this file should contain a copy of PsyScript 3 and associated sample projects and tutorials, downloaded from its homepage. If you want to know more about it, see that page.
If you just want to read the documention for PsyScript, click here.
If you want to work in PsyScript, you want the editor, which you can find here.
Depending on your platform and setup you may not get an editor window when you click on the above link. Common problems can be solved as follows: