Create a Database Environment Mac OS/SQL Developer

Hi I am very new to all of this. I am trying to prototype an function on my local machine. I am using SQLDeveloper and trying to understand what I would need to do to create a database locally. I'm probably using the wrong language so I will try to be more specific. I don't have access to a server where I can build this database and I would need to do it locally - how would I set up my SQLDeveloper to use part of my hard drive space a server where I can build the database?