Sample short story release form for script adaptation?

I don't even know how to ask this right. I'm adapting several short stories written and published by friends into short film scripts. I'm looking for a sample release form or contract that says, basically, "I'm allowing this screenwriter to adapt my short story into a short film and give him rights to make it into a movie and give the filmmakers rights to show and distribute it", etc, etc. I believe Stephen King had something similar but I can't find it.

Does this make sense? Perhaps it would also help to know what terminology I should be using so I can ask the question more succinctly.

Thank you

Let's put things into perspective: the budget for the first short film I did based on an adaptation was about $50, which was about $50 more than I could really afford. The result was not particularly good, I just need some sort of legal clearance to show it at festivals. As my income and the quality of film grows, I agree that hiring a lawyer is a valuable next step. But this first one just needs some sort of agreement in place as a formality. So a boilerplate would be fine for the short-term.