Besides regular articles about the game content, many players like creating their own guides about various features or strategies you can use in the game. You can find a list of such guides here, as well as a short instruction about how to create such guides yourself.
To create your own guide you have to create a new page (here) beginning with "Guide:" and then the name which would suit your guide the most. If there are similar guides already created, try to come up with a different name or differentiate yours by using your username.
Then fill the page with your own guide! All guides should have a similar structure which is indicated in the example guide. In the beginning indicate who the author of the guide is. Then in the "What is it about?" section describe shortly what your guide focuses on. In the "Introduction" section describe the main issue, the main problem which you attempt to address in your guide. Then divide your guide into a few parts (if it's long enough), each with its own heading and name, like "Part 1: Active trading". After you've written all parts and essential text of your guide, include a shortish "Summary" at the end, which would conclude your guide and sum up your main tips you want to give to other players.
The structure presented above is only an advice, you don't have to stick to it if you have better ideas. Just remember to make your guide easy to read and understand for others.
Screenshots and videos
Guides can also include screenshots or videos. Try using captions which would give an idea what the screenshot or video is about. Post your screenshots as thumbnails so they align with the text correctly and don't disturb these users who are interested in the text only.
If you like, your whole guide can be a single video! Then just include the video in your guide, but don't forget about a short summary of the video - so that users can know if that's exactly the video they want to watch.