If you want to change the color of all the links on the page, put it in the <style> tag in the header. You can also change the colors depending on whether the link is visited, unvisited, active, or being hovered over. (I don’t know how to set those qualifications if you’re doing it on one specific link in a style attribute).
<style type=“text/css”>
a:link {color:#FF0000;} /* unvisited link */
a:visited {color:#00FF00;} /* visited link */
a:hover {color:#FF00FF;} /* mouse over link */
a:active {color:#0000FF;} /* selected link */
</style>
http://www.w3schools.com/css/css_link.asp