To attach a photo or a video it is very similar.
Please note that you may need to downsize a photo if it is too large.
This saves space on the servers.
To attach a photo, click on the insert photo button:
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Select the photo to upload by browsing to it and then click upload files.
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Post as normal. To help... I made this quick video. Please ignore any background pup sounds and I hope this helps.
Link with additional information from FAQ section: FAQ Section on Attachments