Music folder of PSP (Portable Sony Playstation)

where is this located into "H:\PSP\MUSIC" (where "H" is the drive letter of your PSP).

The MUSIC folder must be inside the PSP folder at the root level of the Memory Stick. To open it with Windows Explorer:
1. Open Windows Explorer
2. Open the mounted drive of your PSP (it was "H" in your case)
3. Open the "PSP" folder
4. Open the "music" folder
5. Learn Windows/Mac OS/Linux basics

Depending on a PSP firmware version, your PSP will recognize any MP3s or even AAC .MP4 files.

After copying music to "H:\PSP\Music" (where "H" is the drive letter of your PSP) and dismounting your PSP you can play at:
1. Navigate to Music -> Memory Stick
2. Hit the X button
3. Select the song you wanna play.
4. Hit the X button again.