I'd recommend using imgur as there is no captcha and you can edit the size more. If you use firefox, you can get the plugin so all you do is right click and choose an upload options.
Look for the image link ending with.jpg, .gif, .png and so on. If you can't get to that, just download the picture to the desktop and upload it from there. Also click off the arrow where it says remote file whatever on the image upload on the forum, otherwise it will become a thumbnail.