How do I retire the jersey of the player?

Well, im not really going to retire someone's jersey but when i tried, i really have no idea at all, so how do you retire jersey of a player?

If I remember correctly, when a player retires, you will receive a message and you will be able to retire his jersey if you want to.

That's correct, you're given the option of retiring a player's jersey through a message in your PDA when they retire. They must also be currently playing for your team, so if you traded away an aging star and they subsequently retire you can't choose to retire their jerseys (contrary to real life where that does happen).