Applying what you have learned about portrait photography, you will create a movie poster using multiple portrait photographs. Your design must incorporate at least five different portrait images, but it can contain several dozen. How you lay them out is up to you; the most direct way would be to use a strict grid, but that could be quite dull. Consider using diagonal elements, or photos placed slightly out of skew. Consider scale and shape. Think about the edges of the images—they need not be straight, clean edges. Consider adding graphic elements (shapes, colors) to break-up, sit behind, and/or overlay your images. The images themselves can (and should) be retouched & modified in Photoshop. You can tint them, saturate them, desaturate them, add effects, etc. You can cut-out the backgrounds and drop in your own. You can do just about anything, as long as it makes sense for your design.Have fun with it.
You must also include a title for your movie. You can choose your own title, but if your stuck, here are a few: "Black and White," "Conspiracy," "No Tomorrow," "The Itasca Incedent," etc. Think carefully about both the placement of the title and the typeface you use.
Also, list the names of your actors (your classmates). These should be placed on or near their images. Consider carefully your typeface.
In addition, you must incorporate all the junk that falls at the bottom of a movie poster (credits). I'd recommend copying a real one and then swap out the names, using your name and friends' names. Don't feel like typing? Download this sample file. It's important that you use a compressed font similar to the ones used in actual movie posters. Here is one such font. And here is another. You can find more on-line, just search "movie poster font."
The poster may contain other images as well (landscapes, backgrounds, full-body shots) as long as you include the reaquired portrait images.
You also could incorporate a tag line of some sort ("In space, no one can hear you scream," for example).
The final design can be laid out in InDesign or Photoshop.
Consider the project to have four different stages: