I'm going to explain this artcile with "Notepad" applicaiton. After reading this post, you'll be able to launch the "Notepad" application with a keyboard shortcut in Windows.
Locate the program and right click on it to get a context menu, choose properies.
You'll get to see the properties dialog box as displayed below
Place the cursor in "Shortcut key" field and choose a key. Just press "S", you'll get to see "Ctrl + Alt + S".
Click "OK". That's it. You're all done. Just press "Ctrl + Alt + S", Notepad program will be launched.
You can assign keyboard shortcut to any Windows application.