If you want to install Oracle SQL Developer on your Windows computer for free, check if you meet the requirements and then go through the instructions mentioned here.

This course maps directly to the Database 12c: SQL Fundamentals 1Z0-071 exam, which is one of two exams required to earn the Oracle Database 12c OCA certification.

Starting with Oracle SQL fundamentals, and learning from experts with a minimum of 15 years' industry experience.