Defense of The Ancients (DOTA) is a "custom map" for Warcraft 3
It is a relatively small file, circa 2mb in size.
You must have Warcraft installed first and updated with the latest patch.
Then copy the map file into your map directory.
Ours are stored in C:\games\wc3\Maps\Download
If you were to join a multiplayer game of DOTA and you did not already have the map, it will be automatically downloaded to your computer.
No probs over a LAN of course but this could be problematic if you are on the internet, especially via DIAL UP.
If you're in the area of GATT HQ, we can always configure it for you, no probs.
