authentication - PHP using another sites login? -

I am creating a login system for a server, I am starting to launch Minecraft for popular games when I register system I was realizing that a game could pretend to be a game owner when they did not. One way to solve it would be to force them to go into the game and confirm it, but I thought that is a simple idea: using Minecraft.net authentication.

I am looking at this site:

But I do not know exactly how to log in to my Minecraft using the given forum, and even then login Receiving the response.

View source HTML code & amp; You will find a lot about it)
Examples:
https://login.minecraft.net/?user= "+ loginNameUrl +" & password = "+ passwordUrl +" & amp; Version = 13
Use JS to execute the query in this way.

Maybe you should copy some JS from the site ...: p