As I posted in the other thread, your network setup can play a huge part in the way to setup your router for hosting. As you said you have hosted before using a Netgear router, I'm going to assume your network is fairly simple with one router only.
You can use Airport Utility (it should be found in the Applications/Utilities folder) to setup a static IP address which may prove easier to do than manually configuring it in OS X. I only have an Airport Extreme, however I'm fairly confident that the process is identical.
In the Manual Setup of your Time Capsule in Airport Utility, click the Internet tab/button at the top. Judging from what you've posted, you should have a DHCP and NAT tab just below as well as the Internet Connection tab. Click the DHCP tab.
Towards the bottom is a box labelled "DHCP Reservations". Click the + below it to add a new IP address reservation.
In the next screen, type in a description of your computer. This is used for your reference only (so you can tell the reservations apart). I'd usually stick the computers name in here.
You will be reserving the IP address via MAC address (MAC not Mac - it is a unique identifier for each network card). Make sure it is selected and hit continue.
As you will be running this on your MacBook Pro, you can click "This Computer" to have the MAC address entered correctly. If for some reason it is not found correctly or you are running Airport Utility on another computer, you can find your MAC address in System Profiler in the network section (I'll edit in the exact place when I'm out of bootcamp). Enter an IP address you wish to assign to your Macbook Pro. It can be anything in the range of 2-254, it doesn't particularly matter. This IP address is now going to be your new static IP address.
In the NAT tab now, ensure "Enable NAT Port Mapping Protocol" is ticked and then click "Configure Port Mappings" (port mapping is port forwarding). With this new window, click the + below the empty box. You now have to fill in the port forwarding details that Warcraft will use. Warcraft only use port 6112 TCP meaning the entries you need are as follows:
Service: Custom (you cannot select this as it automatically chooses it)
Public TCP Port(s): 6112
Public UDP Port(s): Leave blank (Warcraft doesn't use UDP)
Private IP Address: The static IP address you create with address reservation above
Private TCP Port(s): 6112
Private UDP Port(s): Leave blank
Click continue when this is completed.
Add a description for this rule (something like Warcraft or Battle.net or similar, again for your reference only). You do not need to advertise the rule with Bonjour. Click done. You should see your new rule added to the box.
Update the router with the new settings. Depending how your network is setup, you may be assigned the static IP address once it comes back online. If not, restart your MacBook Pro.
Final step, load up Warcraft and go to Options->Gameplay. Just double check the Game Port is 6112 to match the port mapping rule.
That's all there is to it.
