4. Copy and paste the BBCODE in the message text.
DONE!
The pasted BBCODE is something like this:
[img]http://fivearts.org/fileserver/images/2018/01/23/quiz3Tientai.jpg[/img]
Here, quiz3Tientai.jpg is the uploaded file name.
Depending on the image, your may need to adjust the size for better viewing. For example, my image is too big for the screen, so I adjust it by adding "width=300".
[img width=300]http://fivearts.org/fileserver/images/2018/01/23/quiz3Tientai.jpg[/img]
You can fine tune the size by clicking <Preview> on your post. When you're satisfied, you can click <Post>