Cynthia has provided an excellent
demonstration on how to attach an image to this forum.
However, it is not clear to everyone how to resize the image so that it fits the forum's size-guidelines (image cannot exceed 600 pixels high by 400 pixels wide).
Here is a basic overview using Adobe Photoshop. If you do not use Photoshop, look carefully at the imaging software you're using; most operate along the same principals.
Step one:
At the top of the page, along the menu tabs, look for the one labeled "image" and select. A dropdown menu will appear. From this dropdown, select "image size".