Everybody has something to share, but maybe you have a lot of things to share, try MediaWiki and have your own wikipedia on your website.
Below ther is a description about MediaWiki.
MediaWiki is a free software wiki package written in PHP, originally for use on Wikipedia. It is now used by several other projects of the non-profit Wikimedia Foundation and by many other wikis, including this website, the home of MediaWiki.
To download it click here.