There are two methods to screenshot your Android Device. One is with rooting and the other is without rooting.
- First Method (Without Rooting):
Older versions of Android doesn’t give a simple option to take screen shot directly from the device. Apple’s iPhone has a handy feature which allows to take screen shots by pressing Power+Home button. The same way, Android also have added the Home+Power or Home+Back+Power or Power+Back button. Some combo works. It mostly works on all Android devices running versions 2.1 and up. As soon as you press a combo, you hear a click sound indicating the screenshot it has taken. Now your Gallery contains the picture.
- Second Method (With Rooting):
First, root your phone using the guide given here. Then install this screenshot application (Screenshot UX Trial) which actually requires rooting. I guess you peeps have the common sense to follow the on-screen instructions provided by the application you downloaded.