Research superheroes by reading comics, watching other superhero movies or cartoons, and researching the back-stories of popular superheroes. By searching online, you can find the history of hundreds of superheroes to use as inspiration for your own story. Keep companies like Marvel and DC Comics in mind during your research, as these are two of the major American comic book companies, known for heroes like Wolverine, Spider-man, Batman and Superman.
Take your research and write up a script. The longer your script, the longer your movie. Keep in mind that the quality of your screenplay and dialogue will directly impact the quality of your movie. It's important to develop original, interesting characters that are unique and your own. Try coming up with new approaches to old ideas. You're only limited to your imagination and the rules enforced by copyright laws.
Edit your script and begin casting. Depending on the budget of your film, you can either hire professional actors or employ friends who will work for free. Decide who will be best for the roles in your script, and have different people try them out to see who best suits your vision. Print out copies of the script for all the people working on the film so they can prepare for their roles.
Design your set and costumes. If you're not skilled with sewing, try visiting second-hand and Goodwill stores to save some money and see what you can scrounge up. Since they're your characters, you have the liberty to decide what they'll wear. Be creative and see what you can find, keeping things like setting and personality in mind. You can also find all of your props at these stores.
Get filming and editing equipment, a crew and start filming. If you don't have a lot of filming equipment, you won't need many people working behind the scenes. When filming, consider things like lighting, atmosphere and placement of people and objects in a scene.
Edit your film, adding sound effects, music and credits. If you have the proper equipment and software, you can easily do this using your computer.