Because the Creative Commons provides such a simple way to know what media you can and can't use, a lot of search engines have integrated Creative Commons filtering to ensure they only give you results you can use. When using a search engine that supports Creative Commons filtering, you usually just need to check a few boxes to make sure the media you find are licensed for your use.
When using a Creative Commons friendly search engine, you'll want to look for a setting that controls the license of the search results. For example, Google Image search has a dropdown that lets you select from a handful of different Creative Commons licenses.
In general you should look for media that is licensed for non-commercial use. If you plan to make any changes to the media you find (such as adding text to an image) you'll also need to make sure you have the right to modify, adapt, or build upon your search results.
When you find an image or other media file you like, make sure that you not only get a copy of the file, but that you also keep track of the information you'll need to give credit to its creator. For every file you want to use, follow these steps:
Found a bug in the documentation? Let us know at email@example.com