It's a lot easier to show you what highlighting is, rather than explaining            it. So examine the image below, which is what your letter should look            like so far:
The two lines with the blue background have been highlighted.            When you highlight some text you can do things with it. You can change            the size of the font, underline it, make it bold, delete it altogether,            and many other things. But only the text that you have highlighted will            change. The rest of your document will remain unchanged. So if we were            to change the size of the font in the document above, only the two lines            that have been highlighted will change size. Highlighting is very important            in word processing.
So how do you highlight some text?
There are quite a few different ways to highlight text. We'll go through            a few now. Practice them as you go along.
How to highlight an entire document
You can highlight your entire document from the 
Home tab at            the top of Word. On the right hand side, you should see an 
Editing            section:
Click on the Select item to see a menu appear:
In Word 2010 you'll see an extra item on the menu, right            at the bottom:
Click Select All from the menu to highlight an            entire document. To get rid of highlighted text, click anywhere in your            document with your left mouse button.
An easier way to highlight all the text in your document is via a keyboard            shortcut. Hold down the CTRL key on your keyboard. Keep it held down            and press the letter A. This is will select all text. (This shortcut            works in other software, not just Microsoft Word.)
How to highlight an entire line
Most of the time, though, you won't want to highlight the entire document,            but just sections of it. You can highlight an entire line with just            one mouse click.
To highlight a single line, move your mouse over to the left margin            of your document. As in the image below:
If you can't see a ruler at the top of the page and the            left of the page, click the tiny icon in the top right of Microsoft            Word:
Another way to display rulers is from the View            tab in the Ribbon at the top of Word. Locate the Show/Hide panel,            and the click the Ruler item.
When you move your mouse pointer to the margins, it will turn into            an arrow. When it does, click your left hand mouse button once, then            let go. A single line will be highlighted.
You can use the same technique to highlight more than            one line at a time. Instead of letting go of the left mouse button,            keep it held down. Then move your mouse upwards or downwards in a straight            line.
Let go of the mouse button when you are satisfied.
Highlighting blocks of text
This one is a little trickier, but not too tricky. To highlight a block            of text, do the following: