Cannot Add Images to thread

When I'm trying to insert image to any thread of mine it says "Add an Image from Url". So I upload image to online source and put the url but image not showing.

Most image uploading sites have different links you can copy and paste. The one that works falls under "forum bb code." You can copy and paste that directly onto the thread and it will display the image. Some links will have a redirect included in it so you will need to remove that part.