There are many ways to take a screen shot on an Android device. The simple way to capture the screen on Android is to press and hold Power and Volume Down buttons until you hear a camera shutter. The image will be saved in a Screenshots directory and is accessible via the Gallery. There is also a way to capture a screen shot from your PC.

Connect your phone to your PC and make sure the phone is turned on. Then check to see if adb is installed by opening command prompt and typing:
adb version
If you see "Android Debug Bridge version 1.0.xx" then your all set. If not download ADB by searching on Google for it. Next make sure your device is recognized by typing:
adb devices
If you see a device on the list your good. If you don't see one, go to the manufacturer's website and download the device drivers.

Make a new folder on your desktop and name if "Screenshots" or something like that. Next open up thta folder and hold down the shift key and right click at the same time. You should see and option called "open commend window here" and click on that. Then type this:
adb shell screencap -p /sdcard/screenshot.png
You can change screenshot to any name you want. After you have done that type this:
adb pull /sdcard/screenshot.png
That will copy the screenshot from the phones SD card to the folder you opened the command window in. Now your all done!

If you need any help just leave a comment as always.