How to put out a Casting Call

This is another segment in my "Screenplay Writing 101". I had to do some research again to find out about the ins and outs of this part of getting a film ready for the production part. I don't think the "casting call" is really the responsibility of the screenplay writer but I wanted to understand how to go about it any way. I also wanted to share this information with others who are getting into the industry. Let me see what some seasoned film makers, directors and producers had to say.