This is how you can add image if you have the permission
Upload your image to site like
https://imgur.com/.
You can click the dropdown list on the right of the "Copy" button, then choose "Get share links", and copy the one for "BBCode(Forums)".
Use the following code in your post, your image will show:
Code:
[img]https://i.imgur.com/AGJFpAc.png[/img]