Pro Evolution Soccer Stadium Studio 2009 is the latest installment of the community developed freeware editor by liberostelios. As its name mean, the editor allows you to modify and create your own stadiums for the PC game version, in fact there are a lot of kits developed by different PES community members that were created using this tool.
It actually doesn´t have an official website but the author have some deals with community sites to host the setup files. Unfortunatelly the application doesn´t include a detailed "how to" documentation since its not targeted for amateurs so you should get your tutorial on the community forum or have some experience to get results.
On the other side, there are a lot of tutorials available online and if you are lazy enough to skip creating your own stadium, there is always available for download, most popular completed stadiums that can be import it on the game with another software, in fact once you complete your own stadium you need to use another software to import it in the game.
Is true that PES Stadium Studio 2009 isn´t focused on the average PC gamer but thanks to this program there are a lot of community created downloads that makes the game must insteresting and there is alway a guy that want to do his own stuff, way to go liberostelios!