Library for power supply

how can i get a 12v power supply? someone has the library?

Depends on what kind of 12V power supply you need and for what. If you intend to use it on a PCB you will need to provide a data sheet for the supply you intend to use (as they are all different) and likely create a custom part. If you only need a source of 12V (such as from a wall wart which connects via a barrel connector) then there are barrel connectors in core parts. A google search of the form “fritzing part 12V power supply” turns up a number of hits. In addition I have made a number of parts for various power supplies over the years that don’t necessarily show up (as they are not specifically 12V probably.) Basically more information about what you need is required to give you an answer.