how to block and limit in specific port only???

hello to all guru i need your help how to mangle in youtube and how to block friendster in specific port i have my 5 port mikbok in ether3 its a office network, my boss wants to block friendster in office network only and i have not try to setup this scenario and also how to limit youtube streaming in ether3 only

thanks thanks thanks

i now what you means
you can read that http://mikrotik.unimedcenter.org