Look online on independent film sites or Craigslist. You can go to Craigslist or these film sites' forums and put up an ad seeking a producer. Just include what kind of specific functions you'll need from your producer (money, equipment or production) and your contact information. Include a story synopsis so that potential producers can get an idea of what kind of film you want to make.
Enter your short film's script into a script contest. There are hundreds of script-writing contest that you can find on the internet. Some of them offer only a cash prize, but many offer the opportunity to meet with producers to discuss your potential film.
Send a proposal to a media or production company. While most big production companies will specifically only make feature-length films, there are some that set money aside for short films. Companies such as Tauihu Media will sometimes finance a short for up to $90,000. You'll need to send them copies of your script, budget breakdown and some notes -- including ideas on how the director wants to shoot it. If your director has any previous shooting samples, send them a DVD of that as well.