Before posting an image to the Apple Support Communities, you may want to read on how to capture an image on your Mac:
The menu of options when posting a post on Apple Support Communities is in the bar below:
As you'll see there is a Camera Icon to post images in the center of the toolbar. It is the one on this image, to the left of the divider that shows
the letter A and the Smiley. Click on that icon, and you will reveal this screen:
Make sure to choose an image, and then you can insert the image, if it follows the types of images that are possible. Sometimes you may have to switch the toolbar type a couple times through the menu on the upper right corner of the post to get the Insert Image to no longer be gray.