Aperature and resizing

Hi everyone...I am hoping I am just missing it, but is there a way to take a picture and just resize. I don't want to crop it. But actually resize to upload to the web.

I have a picture and on the application on the web I am trying to upload and am getting that it needs to be smaller than 5242880 bytes.

I was thinking aperature would do that but I can't find it.

I have iphoto, aperature, and Preview...I do not have photoshop....

is there a way for me to do resize it. I would love to do multi pictures at one time, as I will be needing quite a few on the site.