It is against the rules of this forum to discuss ways to get around security measures.
I think a more fruitful line of inquiry for you would be to discuss with your step-father the reasons why he has blocked those sites.
I know for a fact that MySpace is heavily targeted by creators of malware, spyware etc. and that using that site can seriously damage the computer and compromise your sensitive information. It is possible that the other sites you mention are equally targetted, but I am unfamiliar with them so I don't know.
Orange Blossom