As a student, I am required to install Windows Server 2003 trial software. I downloaded the program but cannot install it. The program has an iso extension. Can anyone tell me how to get it to install? There is no exe file.

That's funny, Microsoft trial software is never delivered as an ISO file.

I'll modify Need's answer slightly. Microsoft doesn't deliver trial software as an ISO file. Which means the file you got was not from Microsoft and is, most likely, an illegal copy.

Your school should provide you with legal copies.