Save and load function


So lets say I have a online game where I will have everything that is going on in the game, assigned to variables. I want people to play the game from their own computers through the website and I want them to be able to save and load their place in the game. If this is the first time they have saved, it will ask them to make a login and a password. All of the data should be stored on my server.

Which is the best way to make this happen? Is there any links to tutorials for it?