There are a bunch of different ways to capture what's on your screen and/or a specific window on the screen, and you're right that the easiest is probably print screen (usually a function key labelled "PRT SCRN" or "PRT SCR", as you suggest). Problem is, what it does is copy what's on the screen to the copy/paste buffer, so if you're hoping that you'll push the button and have a file you can easily attach to an email for your brother, well, not so much.

What you can do if you want to work with print screen, however, is to push the function key to capture the screen in the buffer, then launch the "Paint" program and immediately choose Edit --> Paste. Now you'll see your image and can use "Save As..." to create a file.

But there's a smarter way, a way that's more slick and easier both, and it's a little utility included with Windows called Snipping Tool. Let me show you...

First off, you can launch the program by just typing in the first few letters of its name into the Start menu, rather than having to find it in your system, often an alarmingly difficult task. Before you type it in, here's what you'll see:

Start typing into the box, even just "snip", and you'll immediately see matches show up:

The app matched is what we want, Snipping Tool, so click on it to launch it. It pops up a tiny little window without much fanfare:

At this point you can click on the "New" button and select screen, window, or area, but by default it's a click-drag region that's easy to work with, so let's just stick with that.

Don't click on anything, just move the cursor to the top left of the region you want to capture. Now, click and hold down the mouse button, while dragging the cursor to the opposite corner of the region.

Part way through, here's what I see:

Notice how the area within the rectangle is in vivid color, while the rest is a bit greyed out. That's normal. Just drag to the other corner so that the region is defined (don't worry if it's perfect, you can fix it later) and, finally, let go of the mouse button.

Instantly, that region will be snapped and the image pasted into the save window in Snipping Tool:

At this point I can use the rudimentary edit tools included in the Tool to crop and manipulate the image, or I can just save it to disk for later inclusion in a document, Web page or email. To do that, just click on the floppy disk icon adjacent to the "New" menu option on the top left:

There are a number of different graphics formats that the program can use to save the image, but unless you have a reason to choose otherwise, I recommend Progressive Network Graphics (aka ".PNG", or "Ping" graphics). As you can see, I'm giving the new graphics file the name "devices-and-printers", though I'm not quite done typing.

If you forget to save the image and just click the close button, by the way, Snipping Tool's got your back:

Handy indeed! Armed with Snipping Tool, you can now take screen captures, window captures and even save specific graphical elements or icons directly to your computer desktop. Nice.