It depends who you are and where you are. If you are at home there is software available to load on your computers to monitor sites (cybersitter, netnanny, etc). You have to have adminsitration rights. You can also monitor and administer sites through your router interface (usually
http://192.168.0.1) if you have rights.
If you are at work, then obviously you have to have adminstration rights to that machine. You should also check your companies ethic rules or you could find yourself in some trouble. I would avoid this at work if you don't know what you are doing. Someone with decent IT knowledge will hunt you down.