Is there a reason i cant use two controllers on my xbox 360?

my friend let me borrow his 360 controller but it wont work it just keeps blinking what does this mean?

You have to sync it with your Xbox. That blinking light means that it is looking for an Xbox to connect to.

There's a round button on the front of the Xbox 360, to the right of the two memory unit slots. Press that button when the controller is hunting for an Xbox. Use Your Xbox 360 Wireless Controller

Before you can use your Xbox 360? Wireless Controller with an Xbox 360 console, you need to do two simple things:

Insert a battery pack. The wireless controller uses only the AA battery pack (provided) with AA disposable batteries or the Xbox 360 Rechargeable Battery Pack (sold separately).

Wirelessly connect your controller to your console.

Insert Batteries

To insert batteries into the wireless controller AA battery pack:

Press the tab on the top of the AA battery pack and pull down to detach it from the controller.

Insert two new AA (LR6) batteries with their positive (+) and negative (–) ends positioned as shown on the underside of the battery pack. For best performance, AA rechargeable batteries are not recommended.

Slide the AA battery pack back into place on the controller and push it in to lock.

Connect Your Controller

Up to four controllers, wired and wireless, can be actively connected to a console at one time. Each connected controller gets a quadrant on the Ring of Light. Before you can connect a wireless controller, at least one quadrant must be free (unlit). To disconnect a wireless controller, press and hold the wireless controller Xbox Guide button for three seconds, and then turn it off.