- The text, image, video or other files is an original creation by yourself.
- You have permission from the original author to upload it here.
- It's public domain or released under something like the Creative Commons license
Nearly all images, text, video etc. do not meet these requirements. The only exception where you can use copyrighted material is if it falls under the Fair Use clause which is fairly limited, brief snippets of news articles would be an example of "Fair Use".
There is more detailed information here: Quoting and Uploading Copyrighted Material