You can't. HTML is a computer language (text) not a picture format. For a picture the HTML code looks like this except ( and ) are replaced with < and >.
Try right clicking on the picture and checking the URL. The extender on the file name, in the example above ".gif", should tell you what format it's in. There are many different picture formats beyond gif, jpg and bmp which are the 3 most common. Tif, png and wmf are also fairly common but not used much on the web.