As mentioned earlier, information on Wikipedia has to come from reliable sources. This means that you can't write from your personal knowledge or experience. Having this knowledge may help you write better, but ultimately the information has to come from somewhere else.
With some exceptions, these sources should also be independent.
Generally, a source is considered reliable if it has some sort of editorial oversight and a reputation for accuracy.
Usually reliable
Newspapers
Magazines
Scholarly journals
Books and websites by reputable authors
Usually not reliable
Social networking sites
Blogs
Wikis (including Wikipedia!)
These sources must be cited (referenced) in an article. To learn how to do that, go to the introduction to referencing.[1]
A source is independent if it isn't connected in some way with the subject. Wikipedia prefers independent sources because there is a much lower chance of bias.
Not independent sources
Official websites
Press releases
Interviews (even if they are published in a reliable source)
Non-independent ones can be used in limited cases. These cases include things like basic information and claims made by subjects about themselves. Keep in mind that these must still be cited.