trying to get Oracle SQL Developer to work on macbook pro

I have a MacBook Pro running OS-X 10.9.4. I am trying to get Oracle SQL Developer version 4.0.2.15, build 15.21, to allow me to enter and run code. Everything seemed normal until, when I first ran SQL Developer, it asked me to set-up a "connection". I must have got it wrong, because when I clicked "Test Connection", I got these two error messages:

IO Error: The Network Adapter could not establish the connection

Vendor Code 17002

I Googled "Vendor Code 17002", and the 5 or so entries I examined all said something about non-existent or non-running listeners. Unfortunately, the code solutions I examined were all Windows-based.

What I am hoping for is a set of step-by-step instructions, including file names, file contents, and complete file paths so as to allow me to enter and run code.

Thank-you very much.