First of all, see the topic How to make your Pictures clickable.
To post pictures from google photos, go to drive.google.com (not photos.google.com), click on the folder called "google photos" and find the picture you want to post. Right-click the picture and select "get sharable link". Copy and paste the link and use it for the url that you follow when you click on the picture. Then, use this link:
And replace FILEID with the id from the first link at put it in the img tag.
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