How can il get that cinematic/ film look for my movie?

I recently made a small 10 minute movie using only an iPhone 4s. The quality is brilliant, but I'd like that film look that professional cameras have, and not the "home movie" look. Are there any editing programs like iMovie which can help me achieve this? Not something too complicated, as I'm a beginner in this field.

The film look is rather difficult to achieve with digital. You need a much better video camera than the low-end quality of an iPhone. The cinematic look comes from a few sources: The chip needs to be fairly large. You will need an APS-C or full-frame sensor. The "look" of any particular format (film, digital, micro 4/3, APS-C, medium format, large format) has to do with the size of the film/sensor. The larger the film/sensor, the longer the lenses must be for any given angle of view. That's why a 14mm on Micro 4/3, 18mm on APS-C and 28mm on FF all provide the same angle of view on their perspective camera. Because as you increase the lens length, the area that's in focus shrinks, going to a larger format of camera will therefore produce a unique look that can't be simulated or copied by any smaller format. One of the common cinematic "looks" is changing focus from one point to another while having a very shallow depth of field. The larger formats can do this easily, while the samaller ones (smaller than micro 4/3) will find it impossible to achieve anything like it.

Shooting at 24fps is also a major part of copying the look. It creates a specific amount of blur on each frame that simulates the same blur in major motion pictures. Shooting at too fast of a shutter speed will reduce/eliminate the blur which makes the footage look digital instead of the organic look of film.

Your lighting is critical as well.

If a $500 device (like your iPhone) or inexpensive, off the shelf, consumer-grade video editor could provide "that film look that professional cameras have", the professionals would already be using it and there would be no need for them to be using $100,000 Panavision or Arri cameras or custom video editors that no one else ever gets to use… Because then they get to keep more money on their pockets…

The better the quality of light you shoot with, the better the look of your videos. Invest in a lot of lights.