Edit and change the resources as needed.
What changes do you want to make to the existing resources? Do you have the rights to make changes according to the open license on the work?
You grabbed a picture from Flickr and you want to crop it to remove that blurry finger in the upper left corner. Great, but does the license allow for that edit? Some CC licenses have a "no derivatives" or ND clause. That means you can only use that resource exactly how it's been shared with you. That means no cropping the image, fixing the grammatical errors in a paragraph, or even brightening a picture. This might be new to you, but that's the nature of the license. (In some regions of the world, you can still rely on fair use or fair dealing, aka exceptions and limitations to copyright - learn more about that in this other challenge (TBD).) Using works without the ND clause allows for derivatives, so those are your best bet if you want to be able to edit the resource you're using. But remember that if you're making a derivative of someone else's work and they want you to "share-alike" (the SA clause), you will have to license your derivative work with the same license as the original.
Keep in mind that you can often make these changes and edits to the resource directly, depending on where the resources is hosted. For example, YouTube's Video Editor allows for you to remix CC BY-licensed videos on its platform, and Wikipedia allows universal edits. You can also choose to upload a duplicate instance of the resource to an editing platform and make edits to that. Choose the platform that you are most comfortable with and that allows open licensing.