In general web hosted pictures will have an address. However when sharing a web hosted picture you need to tell the link that it is an image. You do that my adding [img] before address and then [/img] after the address (with no spaces). For example this is a hosted image of the bobber from another site, I right click the image on that site, copy image URL, paste the address in the thread and manually type [img] before and [/img] after...and like magic the hosted image is linked. Some sites do this for you when you copy the image link. Worth noting it is just a link to an image...if the image is altered (under the same name) or moves, the link changes or is broken.
Also worthwhile selecting the option to preview posts as you get to see what going to be displayed before submitting
