Character saving

Hello everyone, so I am not such a programmer as you might guess. I am trying to figure out a system in which you select a character in a spawn menu that will be created. And I will do some inventory systems and so on. However, I want them to be saved. It will be multiplayer game so it has to save the character each time the player logs off. There will be levelling system. It has to save levels too. I can not figure this thing out myself. I am very new. Can you help me please?