Question about submitting images

I would like to submit some images.  However I was wondering if copyright would be an issue.  I'm assuming that people are just finding images on other sites, downloading them and then submitting them.  Is that OK to do?

From the Help section:
Also, how do you submit images?! I can't figure it out.

Image upload best practices

Do not submit images with watermarks! Submit high rez images under 1 meg in size whenever possible.

• Images can include box art, screenshots, concept art, fan art, and more. When uploading images, we strongly encourage users to either associate their images with an appropriate gallery, or create a new gallery when necessary.
• Avoid adding images tagged or watermarked with other sites' URLs.
• No nudity or nudity related fan art on the site. The exception is for nudity that is IN-GAME in the store bought version of the game.

So any images are fine as long as they meet that criteria?

pretty much. If you have any other questions on uploading images ask in this thread