Secret??? to posting pictures

[chunker]

I've tried to post a photo of the new toy hauler but it kept coming out upside down. I took the photo with my phone, attached it to an email to myself and saved to photo file on computer, apple iMac. Photo is correct on computer but ended upside down when attached to a posting. I duplicated the photo on the computer and flipped it upside down and tried attaching that one. Same result it's upside down. Can't find a way in editing the message to rotate it.