I did use the auto img tags and provided the link to the image, but it didn't show
It didn’t show because you put the wrong url in the link. Photo hosting web sites say the image is at a certain url but they lie, what these are is the url to the page that contains the image, not the url of the image itself. That is why you need to post your image as an attachment. Then copy the link to that attachment and paste it in the picture icon when you modify your post.