Here's what you need to do

First you will need the game itself, and that would be c&c red alert 2 + yuri's revenge expansion pack with 1.001 verzion patch. I reccomend downloading this cool cracked pack [I-SERVE] Red Alert 2 Retail (2000-2005) which already has an yuri's expansion with 1.001 V, no crack or serial needed, and the instalation can't get easier. Here is the torrent download link 1: http://www.fulldls.com/torrent-games-1844021.html , 2: http://isohunt.com/torrent_details/153308197/red+alert+retail?tab=summary . I hope you guys know what torrent is? If not, go to www.download.com and download bit torrent or some other program for handling torrent filez and the rest you will figure out easily.
After you have downloaded the red alert2 retail you will find that it contain one ISO file, well, i hop you know how to handle iso files :) If not, i'll tell you; iso file is like an CD or DVD, but imaginable, to run it, you will need to mount the image iso file using programs like nero image drive, power iso or any other! Go to www.download.com and find an program that mount iso files. http://download.cnet.com/PowerISO/3000-2646_4-10439118.html?tag=mncol
You mount that file and find it in My Computer in one of the drives, run, install...pretty simple, you will have the game running.

Next thing you have to do is to download UnderStorm Red Alert 2 Patch, it is just an wsock32.dll file http://www.megaupload.com/?d=4Y9SYDRG. Copy that file into the folder where your red alert game is installed (C:\Program Files\Red Alert 2 Retail) and just paste it there. This little thing will enable lan (it changes outdated ipx protocol do udp, new one ). After you did that enther the game and go in options-network and re-select even if it is already selected network adapter card adress 00 00 00 00 : 00 00 00 00 00.

And the final thing, you will need to download tunngle! http://www.tunngle.net/de/downloads/
This is the key of plaxing online! Download it, install it, registration is simple.. You will find that tunngle has an room for every game ever made, just enter in search field ''red alert'' and you will find an yuris revenge room, enter it, chat a little with people in there... Enther the game and go to NETWORK, not internet! Network! You wind all the guys from tunngle chat in your game loby :)
For any other problems feel free to comment and ask for anything! Enyoy!