Family code on a pre-owned Xbox 360

You would need to contact support and they can help you reset it. http://support.xbox.com/contact-us

Hello Fionaca,

Thank you for posting here on the Xbox forums. We understand you are coming across issues with the privacy/family settings on your pre-owned Xbox 360. We suggest following the steps on this link to reset the family pass code: How
to reset the pass code on Xbox 360

Please let us know if you come across any complications. Hope this helps.

Was the game brand new or pre owned? If it was a pre owned game then it might have previously had a code for the dlc included in the case which now might not be with it as it has been used.

Hopefully this helps!

Its brand new buy it today, the one that says Xbox 360 and Xbox One on it, it has 2 disc

Hello, yes this is the case, you first need to add all of the accounts on your own XBOX 360 (the XBOX 360 where the Family membership is purchased) by recovering the gamertags to the XBOX 360. Then add them to the family account, after that process is complete
the other family members are free to recover their accounts back to their own XBOX 360's.

To use a Xbox 360 via a wireless network you'll have to get a wireless adapter that's designed specificaly for the console. You might be lucky to find a pre owned adapter somewhere that may still sell pre owned Xbox 360 consoles.