Trying to attach photo's for contest:
Ok, let's go through your images one at a time:
http://[IMG]https://www.penturners.org/forum/attachment.php?attachmentid=183739&stc=1&d=1547071809[/IMG]
The first problem is inconsequential - merely unnecessary text, which I've highlighted in red. You can see that it is displayed in your post. The second bit of unnecessary text I've highlighted in cyan. Everything from the & to the end of the url is unneeded, but not at all harmful. I generally delete that part, but it doesn't hurt to leave it in.
I suspect that the real issue is that the image you've chosen to display really is of thumbnail dimensions. When I bring it up in another window, it is a small image.
http://[IMG]https://www.penturners.org/forum/attachment.php?attachmentid=183742&d=1547071809[/IMG]
This image displayed correctly, except for the extraneous "http://" (highlighted in red)
http://[IMG]https://www.penturners.org/forum/attachment.php?attachmentid=183743&d=1547072077[/IMG]
Same as image 2 above.
[url]http://[IMG]https://www.penturners.org/forum/attachment.php?attachmentid=183744&d=15470721[/url]
This time, you've wrapped the image in [URL][/URL] tags rather than [IMG][/IMG] tags (or clicked on the "link" icon rather than the "image" icon. You got a hyperlink to the image rather than the image itself.
[IMG]https://www.penturners.org/forum/attachment.php?attachmentid=183744&d=1547072173[/IMG]73[/IMG]
You have some extra text again (which I highlighted in red) but the image came out correct.
[IMG]https://www.penturners.org/forum/attachment.php?
attachmentid=183745&d=1547072173[/IMG]
Note the line break between "...attachment.php?" and "attachmentid…". That's what caused this image not to display. If you delete that line break, it will work.
http://[IMG]https://www.penturners.org/forum/attachment.php?attachmentid=183739&stc=1&d=1547071809[/IMG]
This one is the same as the first (the image appears to be icon size).
http://[IMG]https://www.penturners.org/forum/attachment.php?attachmentid=183740&stc=1&d=1547071809[/IMG]
Again, (like the first jpg), this image appears to be icon size.
I hope that helps,
Eric