I really like that game and i play it even now after so many years you dont' need a network you can use the internet to play with friends!!!
1st STEP: Download Hamachi ''' ,,,,, Hamachi is a virtual network it is a network but over the internet!!!!!!!!
you can get it for free here: http://www.softpedia.com/get/Internet/File-Sharing/Hamachi.shtml
2- install it and open it in the top there will be a number for instance: 65.028.964.4 This is your hamachi IP.
3- when you open hamachi in the bottom there are three icons 1 for shut down and 2nd for configuration and blah blah blah.
4- you shold click on them and one of them will give you an option to create a network click on it and choose a name and a password for your network.
5- your friends should have hamachi too and if they dont' have they can download it just like you.
6- after your friends install it they have to open it and in the bottom in the three icons one of them ll' give you an option to join an existing network they should click on that after they do that it will ask them for network name and network password just give them your network name and password this should do now after your friends join your network you will be able to see them and chat with them using HAMACHI.
7- now you are done with hamachi just minimize it (((do not close it)))!!!
8- open your red alert 2 and click start new server just like what you did for LAN, And they should be able to see your host and join you.