I already asked a simalar question,but i have my own website,cont. in details?

i have my own site about cars,and i was curious how some websites like myspace for example have people create profiles,thats what i want to do,i want people to visit my page and be able to create there own profile and upload pictures...how can i do that,what program do i have to use,format? is this something i would have to pay for,is anything what im looking for free?any help on this is appreciated