The left margin is how far from the left edge of the page the text will start. Similarly, the right margin is how much empty space on the right there is. The top and bottom margins control the empty space on the top and bottom. The default margin for all of these is one inch. We recommend 0.5 inches to save paper. More will save more paper, but some printers can't print with very small margins.
Once you have changed the margins, you can set them as the default margins by pressing the button in the bottom left corner.
Great, you're done!
In Word 2010, the spacing is automatically set to 1.15 spacing and "Normal".
The "Normal" means that when you press enter, it skips down two "lines". You should probably set the normal to "No Spacing", which can be done by selecting all your text and clicking the "No Spacing" button.
The button to the left of the paint bucket is the spacing control.
Click it and you will see the current spacing (1.15 by default).
For normal writing, 1.15 is fine, but teachers often assign double spacing or 2 spacing. This will make for a very long document that requires a lot of paper. If your teacher allows it, you should use 1.5 spacing because it uses only three pages for every four.
Thanks for saving paper!