You need to get some server space somewhere. There's a bunch of photo hosting services out there, many are free.
Does your ISP provide you with webspace? If so, upload it there. Most of them provide about 10megs of space.
Also there's some webhosting sites like Angelfire, etc. but they often don't let you link to them.
After that, just click on the above picture icon

and paste the url between the markups.