This is quite easy for people who know the basics.
Now lets start.
1.There is a key named printscreen key on the keyboard. In many keyboards this key may have a different name. For Example its name on some computers will be PrtScn or something like that. To understand the location of the key an image of the primitive keyboard is given. In the modern QWERTY keyboard the key may be a little left to the key given in this image.
2. Now in the second step this should be pasted somewhere. For example you can paste it in paint.
If you want you can also paste it in anything else like Microsoft Office Picture Manager. Here is a picture of pasting in it.
You can paste the image in any supported image viewer for example windows photo viewer.
Try this and keep visiting