If you want to post a photo for CC - constructive critique - go to the appropriate CC sub-forum.
Click on the Forums tab near the top of the page, or here. Scroll down to the section in the green bar called
CONSTRUCTIVE CRITIQUE - Members' Photos:

Look through there to see what is a suitable place.

If it's for posting a picture of equipment for info only, scroll back up to "Gear Talk" and look in there.
Finally, there the Not For Critique forum when all else fails

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If you need help posting an image by uploading to AP, have a look at
this thread here.