Once your image is uploaded to Commons or Wikipedia, you probably want to use it in an article. Fortunately this works the same way whichever site you uploaded it to. Simply click  on the article you want to include the image in, then add the following where you want the image to appear:
Notice that the caption can contain links.
You can also place images on the left hand side:
See Wikipedia:Extended image syntax for more details on how to adjust the display of images, including their size.