You can go to sites like this in order to upload the image onto other sites like this one. The specific site that I linked gives you the option to edit your images a bit before posting to a website and you have the choice to replace the original or save it as a copy. That's not the only feature, of course, but I think you should check it out for yourself. The codes that the site gives you are what allows you to post the pictures.

If you're already using a site like that, it's possible that you're using the wrong code. Be sure that you're using the correct code. If that doesn't work, then I'm not sure what else to attempt. I try helping people to the best of my knowledge. Sadly, my knowledge doesn't always extend to a certain point for everyone. You'll want to use the IMG code.