Pokémon Red Version/Walkthrough/0001 - Route 1

Speak to the NPC on the left as you head north; they will give you a Potion. Since you have no Poké Balls, you can either fight the Pokémon on this route or run away. Given that your Starter Pokémon is only at Level 6 (assuming you beat your rival), battling some of the Pokémon here is advised to gain some experience. Don't waste Potions at this stage; if your Pokémon is at low health, head directly to Veridian City.