There are two basic ways of creating applications. They are as follows, in order of difficulty (not that any of them are hard): Splunk Web (we will call this the GUI), and handwritten (henceforth to be recognized as FreeForm). In order to create Apps, you, the developer, must have specific permissions within the Splunk instance.
Set up a brand new instance of Splunk with a dev license to make sure that you have all the proper permissions to develop an App.
For the GUI method, the user must be an admin within Splunk; additionally, for the FreeForm method, the user must have server access to the command line with as many permissions as required by the user that runs Splunk.
We will start with the GUI ...