CSS is made up of three parts:

A selector, property and value.

selector {property: value}

The selector is usually the HTML tag you want to define, the property is the attribute you want to change, and every property can take a value. The property and value are separated by a colon, and surrounded by {and}:

body {color: #c0c0c0}

If the value has more than one word seperate them with commas.

body {color: #c0c0c0} 
body,td,th {font-family: Verdana, Arial, Helvetica, sans-serif}

If you make more than one property separate them with a semi-colon ";"

body,td,th 
{	
font-family: Verdana, Arial, Helvetica, sans-serif;
font-size: 12px;
color: #666666;
}

Notice how much easier to read it is if you don't put everything on one line! Also, notice how you can group several selectors by a comma "body,td,th"

You make the selector into a class. You can use this to make different sections of your page appear different by specifying the "class" start with a period such as .title

.title
	{
	padding-left:80px; font-size:24px; padding-top:25px
	}

On your html page place the class like this <H4 class="title">stuff</H4>

Keep your CSS clean and organized by placing comments that are not seen by anyone but you to divide different sections of your style sheet.

/* This is a comment */