hello, as wikipedia is very popular site. so we can write something for our organization in wikipedia?
You can write something, but you can't write a promotional article. All articles especially by new to wikipedia authors are reviewed. If there is no significant content, it can be quickly deleted. https://en.wikipedia.org/wiki/Wikipedia:CSD
Of course you can... You will also help Wikipedia by writing a HIGH quality and an informative article. Just be sure to write for a niche that you know a lot of things, so you can make your post both useful and also interesting for people. And the most important, don't write to sell something, DESCRIBE something, try to tell something new to people!
Yes you could write about anything in wikipedia but you need to remember this to you can't write in promotional way like promoting yourself.
You have already write got answers. FYI The information you will enter in Wikipedia should be focused only information about the topic not any promotional stuff. And all the information you will enter their should be correct.
If you want to get a page on Wikipedia, prepare to spend hours creating the page, have lots of backup references and citations (and know how to format articles in their own markup language which can be tricky), and then to deal with the mods who are there to keep the site clean and spam free. If you can get a link from Wikipedia it's gold but the hassle makes it worthless from a time investment/ROI viewpoint. Don't consider fundamental to your SEO strategy. If you're thinking of using the site simple as a means of getting a backlink you're likely going to go about it wrong and fail to get the link in the end anyway.