Log on to a website that sells film rights, such as Internet Movie Rights (see References below for link).
Create an account with the site. This will require a valid email address and the creation of a password.
Look through the list of available films and choose one that you would like to own the rights to. Sometimes these are obtainable in packages.
Use the site to contact the owner of the film's rights.
Negotiate a price with the seller. This will vary on the different rights that you want to buy. Rights that are procurable are distribution, sales and re-creation of the work.