Extract the IOS image from the zip file. You will need to use a tool like WinRAR or 7-Zip to extract the IOS image.
He downloaded the IOU image from a shared Dropbox link—sketchy, but desperation had no ethics now. He fired up the GNS3 IOU VM, uploaded the image, and created a new “Etherswitch” router template. cisco 2960 switch ios download for gns3