Bitttorent port opening problem

Hi, I'm new to bittorrenting, so sorry if this is an obvious question. A friend gave me information for how to open the port on my iMac so I could start downloading, but every time I try it, I get no connection to the internet. All I get to it step 2, setting the IP address to be static, and that's when there's no longer a connection. Any idea what I'm doing wrong? Here's the info he gave me to follow:


There are 3 things to do. Describing and reading it takes longer
than actually doing it.

(1) Picture 1
In BitTorrents preference, check the port that it expects to be
open. You can change it but I didn't. It defaults at 6881.


(2) Picture 2
Set your computers local IP address to NOT change.

In the computers Network Preferences se the TCP/IP tab to:

(Check and write down what's in all the field before changing
anything.)

-Configure IPv4 to 'manual'
-Choose something like 10.0.0.99 (that will now be your computers
local address)
-You usually also set the subnet mask to 255.255.255.0
-You may have some numbers in the other fields for your cable
connection


(3) Picture 3
Open up Airport Utility...go to the 'Port mapping' tab. Click the
'Add' button.
1-Public Port (The port that the signal comes in that you want
to direct).....set to 6881
2-Private Address (The computer that the signal should be sent
to)......set to 10.00.99 (that's now your computer)
3- Private Port (The port it should now got on that
computer)...set to the same 6881
Click DONE or something and reset he Extreme
Your done. Now try the program again.