Help with .mdl code from the internet

I downloaded a few codes (.mdl) for simulink from the internet but I cant get them to open. I tried to copy and paste in text files, and then open in simulink but that didn't work, then i tried to create in DOS a .mdl file and then use a text editor to open it and paste the code in it, but when i tried to open this .mdl in simulink, it told me that the filename is incorrect or the file doesn't exist.. can someone please tell me how to get these codes from the internet to run the models?