Or you can just click the 'Add image to post' located under the smileys, which opens up a link to postimage.org, allowing you to either upload images from your computer, or load them in from another URL, you also have the option of uploading lots of images at once, which is great time saver if you have more than one image to post. Don't forget to click the 'family safe' radio button, otherwise it won't work.