Internal or external port forawrding?

Hello, when i try to forward ports on my router should i type under "internal" or "external" or both? My specific case would be forwarding 3 ports to steam
Best regards

 

Both.

Your router needs to know what client is using the port forwarding, so you will specify the IP address, the internal port (this will be the port specified by Steam), and the external port, which in this case will be the same port number.

 

So it would go:
my ip adress Start port End port Start port End port typeUDP/TCP ?
thats how it bassicly goes on my router when i enter port forwarding, they give me 2 numbers but i have 4 slots for them ?
Also, here are the ports (i need the first 3 listed)
Can you maybe show me on an example (one of them)

 

https://support.steampowered.com/kb_article.php?ref=8571-GLVN-8711 (the first 3 ports) but showing me how to do 1 is perfectly enough
And here is how it looks when i open the port forwarding page of my router
Note" the drop menu is going over the word "external", i didn't notice this until i already uploaded this picture

 

As an example, this is a range:

https://www.dropbox.com/s/5irn1xgszgux5cz/Screenshot 2014-01-16 15.04.31.png

This is a single port (the enabled one):

https://www.dropbox.com/s/qy5kw10gg3f4p65/Screenshot 2014-01-16 15.06.43.png

That covers you for all of these:

Steam Client
UDP 27000 to 27015 inclusive (Game client traffic)
UDP 27015 to 27030 inclusive (Typically Matchmaking and HLTV)
TCP 27014 to 27050 inclusive (Steam downloads)
UDP 4380

 

Yes i know that, my problem i how to type it into my routers layout
Look at the picture i placed and show me the way you would put one in with my router
Try to be specific whether you are placing the start port end port under just "internal" or "external" or both? Thats the thing confussing me