For the Athens, Greece, you need to apply for a Greece Schengen visa. The following are the steps you need to keep in mind while applying for a visa:

Book an appointment for a Greece Schengen visa to proceed with your application
Download the application form from their website and fill it out correctly
Submit all the required documents along with the form
Once your documents are accepted, you will be called for an interview
Wait for a response on your visa application; it may take up to 15 days or more

We have a comprehensive Greece Schengen visa guide here which provides detailed information about the visa, how to apply, types of visa and more.