Screenwriting : Does anyone have any suggestions in getting funding for a movie trailer or movie? by Robert Sandage

A friend and I are working to get my film script THE POSSESSION OF INNOCENCE funded to create a 3 minute movie trailer to post on YouTube, Facebook, or any social media site to see about finding someone to purchase the script and make into a movie. I have a artist creating a movie poster right now with all of the main characters in the film. When a film company buys the script and if that company wants to take ideas to use for the film posters that will be displayed at movie theaters. I appreciate the help and recommendations that anyone has for me. Rob