To reach Cianwood City, you need to follow these steps:
1. Complete the first three gyms: You need to defeat the gym leaders in Violet City, Azalea Town, and Goldenrod City.
2. Head to the National Park: After defeating the Goldenrod City gym leader, head south through Goldenrod and you'll find the entrance to the National Park.
3. Explore the National Park: This area is filled with different routes and encounters. You'll need to travel through it, following the paths until you reach the east side.
4. Cross the bridge: On the east side of the National Park, you'll find a bridge. This bridge leads directly to Cianwood City.
Important Note: There is no "Cianwood City" in any other Pokémon games.
Let me know if you have any other questions about the Pokémon games!