Unlike some other Final Fantasy titles, you don't 'create' individual characters in the traditional sense. Instead, you begin with four nameless orphans: Luneth, Arc, Refia, and Ingus (or their equivalents in the original Famicom version). Their personalities are fixed, but their combat roles are entirely up to you, thanks to the revolutionary Job System. This system allows you to change your characters' jobs at any time outside of battle, provided you have unlocked the respective job. Each job comes with unique stats, abilities, and equipment proficiencies.
Initially, you'll be limited to basic jobs like Warrior, Monk, White Mage, and Black Mage. As you progress, more advanced and specialized jobs will become available. Experimentation is key! There's no single 'best' job combination for every situation. Consider party synergy: a balanced party with physical attackers, magic users, and healers is often most effective. Changing jobs costs Capacity Points (CP), which are earned through battles. The cost increases with higher-tier jobs, so plan your changes wisely, especially early on.