You can implement the below code into your <head></head> portion of your web page. This is a full example of changing the link properties of your web page. If you wish to just change the link color when moving a mouse over a link you only need the a:hover line.
<style type="text/css">
a:link { COLOR: blue;}
a:visited { COLOR: purple;}
a:active { COLOR: red;}
a:hover { COLOR: green;}
</style>
hover - This is the color that the text is going to be changed to when the mouse is over the link.