How can I Block Sites or ports in a ruter wich use MikroTik OS? Does any one of you knows about this? Please respond...

1. Do a host lookup under your favourite OS example..

[TestBox]# host youtube.com
youtube.com has address 208.65.153.253
youtube.com has address 208.65.153.251
youtube.com mail is handled by 10 sjl-mbox1.sjl.youtube.com.

It should show which ip's handle the site.

2. add these ip's to a address list..

/ ip firewall address-list
add list=youtube address=208.65.153.251 comment="" disabled=no
add list=youtube address=208.65.153.253 comment="" disabled=no

3. You can block the site by adding drop rule under:

/ip firewall filter add action=drop dst-address-list=youtube chain=forward