One way of capturing the whole of your screen is simply to press the 'Print Screen' (or 'PrtScrn') key. Nothing will seem to happen but if you then go to a suitable program (such as Paint or Word) and select 'Paste', the screen shot will be added to the page.
However all of the more recent versions of Windows have a much more flexible utility, called the Snipping Tool, built into them. It allows you to select just part of the screen and also makes it easier to finish up with a jpeg file (rather than, say, a Word document).
To use the Snipping Tool, go to Start > All Programs > Accessories > Snipping Tool. Then use your mouse to drag a rectangle around the required area of your screen (by holding the left button down as you do so). From there, go to File > Save As to choose a name and a file location for the jpeg output.
If the 'send' part of your post means that you want to include the screenshot in a question on AB, please see my post here for instructions on using TinyPic:
http://www.theanswerbank.co.uk/Technology/Computers/Question1312764.html