Illustrations that I have added to Wikimedia Commons and inserted in some articles:
Illustration of the electric field surrounding a positive (red) and a negative (green) charge (click for larger image). I inserted this illustration in the Electric field article.
Illustration of the electric field surrounding two equal charges (click for larger image).
Illustration of the electric field surrounding one positive charge (click for larger image). I'm not quite satisfied with this one, but I don't see any article where it would be obvious to use, so I won't improve it just now.
The easiest way to create a new article is to click on a link to a page that doesn't exist. Typically, these links show up as red links.
You also can use the Search box—on the top-right corner of your screen—to look for an article name. When you are told that the page does not exist, click the link provided. You can also use the Article Wizard.