You're looking for information on downloading the Avatar: The Legend of Korra PSP game. Here's what I found:
Many players use the on PC or Android to play classic titles. Because the PSP had an official Avatar: The Last Airbender game, the community has created "Legend of Korra" mods for it. These mods often swap character models (replacing Aang with Korra) or add new bending effects to the original game's engine. How to Play Avatar Games on Handhelds avatar the legend of korra psp game download
To download the game from the PlayStation Store: You're looking for information on downloading the Avatar: