Iso won't load

[Knifty]

Hi, Im new to emulation so I'm sorry if its something really simple.

I downloaded Dolphin and have watched a couple of videos on how to set it up.
But whenever I try to open Monster hunter Tri it comes up with the error ""C:\Users|Daniel\Desktop\Dolphin\Monster Hunter Tri.iso" is an invalid GCM/ISO file, or is not a GC/Wii ISO."

Can someone please explain to me what I am doing wrong?

Thanks.