This has been an issue in a couple of FanShots and FanPosts lately, so I just want to clear it up right now.
If you are using information from another web site, you should be sure to credit the source in your posts with a link to where you found it, and by naming where you found the information. You can highlight your text and click the icon that looks like a chain link to do that.
Second, if you are going to copy and paste a portion of what they wrote -- no more than a paragraph and never the entire thing -- be sure to include that in the block quote function. The icon looks like some quotation mark.
Using information that is not yours is still plagiarism or a violation of other writers' copyrights, even if done so unintentionally.