Instructions
Go to the DOTA Utilities page for the mana bars. Select either of the two ZIP files to download it.
Select the file after downloading and extract it to the directory of your choice. Open a "Warcraft 3" game.
Press "Alt" plus "Tab" to switch to your desktop. Select the "Manabars.exe" file from the folder with the extracted file.
Select the game again. Open any map to see the mana bars above your units.