If you consider these steps complicated then I assume that you don't want to setup a dedicated server. If all you want is to have friends connect to a game hosted on your PC (not a server running 24/7), then basically all you have to do is:
1) make sure your firewall (if any) allows connections to OA ports
If connected directly to the Internet (using a modem, public IP):
2a) nothing, go to 3)
else (you are behind a DSL router or sth. like that):
2b) configure portforwarding on the router (see manual) to allow connections from outside to your PC
3) find out your public IP and give it to friends so they can connect to your server (you may use a site like
http://whatsmyip.org/ if you don't know how to do that)
4) start OA, click on
multiplayer -> create server and follow instructions on screen to create a server.