Open the emulator and point the "ISO Selector" or "Game Directory" to the folder where you extracted the Naruto ISO. Select the file and click "Boot ISO".
Alternatively, you can also use a PS2 emulator, such as PCSX2, to play the game on your computer. To do this:
Look for a "Highly Compressed" version (usually around 1GB–1.5GB compared to the full 3GB+). Ensure the file format is or .CSO .