RouterOs 3.31 port forwording

Hi to all and what a great product.
I have a question that even though I am sure that it has po-up a million times, still when I try to apply what I read to my routeros It does not work.

My question has 3 parts.

1)I have my routerboard 750g with routeros and it connects through interface-1 with my modem/router to gain access on public internet on the ip address 192.168.1.2. On interface-2 it has the default vlan of 192.168.88.x and I have plugged my switch there. Of of my pc’s lets say the one with the ip address 192.168.88.250 has bittorent installed and I have decided that it should listen on the port 1821. I hav opened access from my modem/router to pass on all traffic from 1821 to routerboard. How to I route the trafic on routerboard to pass everything from 1821 tcp/udp to my pc?

2)If I wish to change that in the future how do I do it?

3)Is there a way to see port mapping as a list?

Thanks guys

http://wiki.mikrotik.com/wiki/Manual:IP/Firewall/NAT#Port_mapping