AppData folder. I find the easiest way to do this is to press the Windows key, and then search for “%Appdata%” without the quotes.
The search should return a folder called “Roaming”, click on there and look for the “X15COIN” folder.  
This is the folder where you need to place the config file

Yes, your conf file name incorrect , should be  X15coin.conf , please update the name ,thanks .