This is all guesswork, but I would guess that wherever you have compiled the driver is not in your PATH variable in which case what I would do is to provide the full path to the 'modprobe' command. So if for example you compiled the driver in /opt/ralink I would try
sudo modprobe /opt/ralink/rt3562sta.ko
I don't know if this will work but it is worth a try. If it doesn't work the alternatives are to move the file to somewhere that is in you PATH variable:
will tell you where those locations are.
Or lastly my least favourite option would be to add the location of your file to your PATH variable for which you need the 'set' command.