Css link style in all pages

i have a css link style in my main page. on the left side of my page with a blue bg i have my links in white color;

a.nav:link {color: white; text-decoration:none}
a.nav:visited {color: white; text-decoration:none}
a.nav:active {color: white; text-decoration:none}
a.nav:hover {background: none; color: yellow; text-decoration:underline}

my question is how can i apply this same style but this in a white backround and changing the links to blue color.
also, how can i apply the css on all of my pages?

by the way im using dreamweaver mx.

thank you!