Go to www.slide.com and make an account. Then you upload your photos and add captions and stuff. Once your done making it, it should have a code for you to copy and paste into the 'about me' section in your profile on myspace. Hope I helped.

EDIT: Yes, you can add on to it. Just go back to your account on slide.com and look at your slides. It should say 'edit' somewhere by it.