The link I gave you above, Barsel, was for a program that can easily resize your photo. (It's not a site that you upload photos to). If you don't want to install that program, another way to resize your photo is to post it into a blank Word document, then right-click on it to access the options to resize it. (You can use other software, such as OpenOffice Writer, if you don't have Word)
Then you can print out the Word document onto photo paper using an inkjet printer and trim off the white area. (If you've not got a printer of your own, mail the Word file to a friend who has).