Just installed Hamachi for the first time.... :shock:
so how does this work exactly?

ok, so there's a little tutorial... :oops:
Ok, I'll explain it simply.
Himatchi allows you to connect to other people across the internet as if they are on the same LAN as you.
There are various networks set up. (such as the one Nick mentioned) When you join a network, you are connected to EVERYBODY on it who is online at the time. (they appear brighter and bolder in the list when they are online) This is good, because you can play KaM. It is bad, because potentially viruses can find there way across. (unlikely though) You can chat with any of the people in the networks you are in, and you can be in as many networks at once as you like. (I think...)
To play with someone over Himachi, you must first find someone who is online and willing to play. If someone comes online, right click on them and click "Chat". You can then ask them if they would like to play or not. Make sure that you're both using the same version of KaM. (e.g. if one person is using 1.3 and you are using 1.32 then it won't work)
To connect inside KaM, you must enter the hosts IP address manually. When you are chatting, organise who will be the host. They can create a game using TCP/IP. Then, the person(s) who is NOT the host must join via TCP/IP. When it brings up that Window that is impossible to read due to a corrupt pallet, enter the Himachi IP address of the person hosting. This is displayed along side their name in Himachi. You can right click on them and then click "Copy address" to make it easier. So enter that IP address in the box, and click ok. (or press enter) Then their game should be displayed in the list, and you can join it. Not that unless you are relatively close geographically then it will lag really badly. (I found it unplayable with someone in China, and China's quite close to Australia)
Also, you should disable your firewall(s) when playing so that it can connect to the other person. (and click allow if any anti-virus program wants to block it)
Hope that helps you,
Lewin.