As Rachana says, post it up to the Mendix Community in Medium. Ryan Mocke or one of the editors will normally moderate the article and come back with suggestions before it is published.
As for content, just try to put yourself in the position of the reader and see if what you have written gives enough information for them to be able to recreate the example easily. The reader should also come away with an understanding of why that approach was used. Plenty of screenshots and diagrams usually help.
Technical writing is a very underrated skill. Best of luck and I look forward to reading your article.
you need to have an account in Medium and share your Handle with Ryan Mocke for it to get posted.