To submit an article to nexus, the first thing you have to do is navigate to a page that displays articles. You can either click on the "Articles" link in the navigation bar, or you can select "Your Page" and then make sure you are viewing articles. Your display will look like the following:

Then click on the "Add an article to nexus" link

You will be presented with a simple form to fill out:
Your nexus login ID will automatically be populated. Add the URL and title of the article. Then add an abstract that describes the article. Other users will view the abstract to decide if they want to read the article.
Select one or more categories (hold down shift or ctrl while selecting to include multiple categories) that best describe the article. If the article does not fit well into any of the categories, you don't have to select one - the article will show up under the "All Topics" view.
Select an experience level - beginner or expert. This represents the experience level that will most benefit from the article. Some articles are clearly targeted at experts, while others are good for beginners or both experts and beginners. If you aren't sure, select 'beginner'.
Click the save button and you're done.
Note - only one article can be created for any URL (the website address of the article). If you attempt to add an article that has already been submitted to nexus, you will receive a warning - no need to worry.