professionally psychology writing course?

You want a class that can help you write papers in psychology?

My suggestion is to take a class at a local junior college, Santa Monica Junior College for example. The class you want is an expository writing class from the social sciences department.

Honestly, writing psychology papers IS difficult. The APA (American Psychological Association) has it's own book you can get at any University bookstore. But practice is really the best way to get better at writing.

I can see why you need it by the way you wrote your question.