The "x" button is the xbox guide button that is in the center of your controller.
1. First, turn on your console by pressing the power button on the console itself.
2. Next, press the xbox guide button that's on your controller. (The button that lights up and flashes when you press it).
3. On the front of your console, just to the right of the memory card B slot & just below the right corner of the DVD tray, there is a small, round connect button.
4. With the both the console & the controller on,(lights flashing) press and release the connect button on the console first.
5. Then on the controller, press the connect button (green arrow, circled in red) that's between the Left Bumper button (LB) and the charging port (blue arrow).
6.The lights on the controller and on the console should continue to go in a circle and stop.
7. The upper left quadrant is controller # 1, the upper right quadrant is controller # 2, bottom left is # 3, and the bottom right is # 4.
8. Once the controller connects the the console,you're all set. Then the next time you go to turn it on, just press the xbox guide button on the controller and it will turn the power on to the console for you.
9. If you ever take your controller and use it on another 360 console, you have to go through the same connection steps as you just did. And then again, when you get back to your console
Hope this helps! Happy gaming!