Warcraft 3

I just downloaded warcraft 3 from bittorent and i recieved this file:
Warcraft III retail.dmg.sitx
now i'm unsure what to do with it. i'm pretty sure its an image but i don't think that the extension is correct but i don't know what to change it to???

any help appreciated :)

get Alcohol 120%, its one of the best image burning software avaible, does all sorts of images

yeah i got alchohol but i can't open the image with it