Port fowarding on openRG modem-router

I have transmission working on my raspberry pi at port 9091. I can access it locally by the IP 192.168.1.34:9091, but I want to access it globally by the fixed IP i've configured.

I've read the OpenRG manual but this part is not well documented, so I couldn't know what I had to do.

Observation: sorry, stack overflow won't let me post any image before 10 of reputation, neither more than 2 links. So I broke up the links, please just copy and paste it into the browser.

Here's the first screen that appears when I try to configure the port-fowarding at the Open-RG modem-router. I click at "new entry" and then this screen appears:

http://ift.tt/1Cu7MpY

http://ift.tt/1Cu7K1j

When I'm asked to select the protocol, I select the "user defined" option, and then this screen appears:

http://ift.tt/1BuQggy

I, of course click in "New server ports" and then:

http://ift.tt/1BuQhkq

In this screen, I imagine that "source ports" are the ports that gonna be visible to the word when they enter mydomain.com:port. So I type 9091 in it (I could type any, but lets make the same as the application port). The destionation port, I presume, is the port of the application, so of course, I made it 9091. So when I press ok:

http://ift.tt/1Cu7K1n

Then what happens is that when I press OK I get:

http://ift.tt/1BuQgwU

What is this? Didn't I already configured the ports? Why is it asking me again to "foward to port"? I though the part that said "source" and "destionation port" were the ports to listen and foward too.

When I select "specify port" I can only type one port number, like the image shows. What is this port: the source or the destination one? This router is confusing! I wish it was as simple as choosing "local ip - source port - destination port", but this router is crazy! Also, I know that transmission is unencrypted so in fact I'm just learning how to do this, because I will set up a nginx or apache proxy (encrypted) that will serve as a proxy for transmission and other applications. But first I need to know how to foward a port on OpenRG.

Also, when I access mydomain.com (which is fowarding to my static IP) it opens the router configuration page :o! Crazy! How do I turn this off? Which port should I deactivate?

Thank you by your help guys!

(please someone upvote my question, then I can properly insert the images for a better reading)