+ First, go to an internet cafe to copy Warcraft III. And don't forget to check the patch. Patch 1.23 will be used to play Dday: Judgement. 1.24+ will be used to play Dday: Revolution.
+ After that, download Garena Client. Website: www.garena.com
+ Go to a Dday Room and play. I think you know how to set up a game.
About always getting disconnected, i think your connection has some problems.