Looking for a tutorial on how to make an OS X Notification Center Widget?

I've never programmed with Xcode/Swift/anything OS X related before, but would like to learn how to make a (hopefully) simple notification center widget that runs a terminal command/AppleScript on click of button A, and another command/AppleScript on click of button B. A title and image may also be nice, but not necessary.

Any pointers in the right direction are much appreciated.