How do I include the "pitches.h" library?

Im confused on how to use this in platorm.io

Which library are you referring to.
Also which platform, board and framework do you use?

Arduino Uno and im trying to power a buzzer

Example of the pitches.h here: https://docs.arduino.cc/built-in-examples/digital/toneMelody/

pitches.h” is not a library on it’s own.
It is just a part of the source code for the example.

So, there is no way to “install” this.
Just create a “pitch.h” in your source folder and copy the content from the linked file above.

There is a “TonePitch” library in the registry: See PlatformIO Registry

This library comes with an example.

To install this library, simply add rodrigodornelles/TonePitch@^1.0.3 to your lib_deps in platformio.ini:

lib_deps = rodrigodornelles/TonePitch@^1.0.3

ohhh ok I was confused by the include! Thanks.