What is Copyright?
Copyright is a law that protects people who create work (novels, articles for magazines, photographs, music, lyrics, games etc).
If you do not obey copyright law in your DiDA coursework there is a good chance you will fail the course.
Whilst you are not expected to be a lawyer, you must make sure you have checked that any material used in your coursework THAT YOU DID NOT CREATE YOURSELF is ok to use for all purposes - including "commercial purposes".
We have to assume that this is not coursework for "educational purposes", we must work on the basis that this is a real project that we are working on for a real "client".
When gathering information (which includes text, logos, photographs, sound, etc), make sure you include details of where you got it from and who owns it. This is particularly true of pictures. Many sites will let you use their material for free (even for commercial purposes) so long as you give a credit on the publication (e.g. "image courtesy of freeimages.net").
You will record all of the above imformation in a "sources table" which is the main way that the examiner can mark this aspect of the coursework.
Images are a particularly powerful way to make an impact in your work. Why not take some of your own photographs, or create images by drawing them in Photoshop/Fireworks/Paint?
Here are some sites I have found that will allow you to use their images for commercial purposes with a credit. Remember to record the details in your sources table.