On iPhone (or iPad I guess) browser go to website https://postimages.org/
Upload photos
Where is says “do not resize my image” click on the drop down and select “640x480 for message boards”
Once photo uploaded, copy the second option “direct link”
In the post you are creating , click on the insert photo icon
Delete the https:// and paste in the link you copied from the postimages.org website
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SEE BELOW THE UPDATED POST DONE ON MAY 3, 2022. IT HAS CLEARER INSTRUCTIONS.