To clarify Murray's answer, there is nowhere to edit the link styles, you need to create new styles for the links.
Your main style sheet does not have a body or a head section, as html pages do, You can indicate different style groups on the stylesheet using comments, if you wish. The theory behind cascading style sheets (CSS), is that styles further down on the sheet can cancel out styles defined earlier in the stylesheet. Organizing a stylesheet carefully is always a good idea.
If you want the link styles to change universally throughout your site, put the styles near the top of the stylesheet and do not put any overriding styles further down on the sheet. Always list link styles in this order: a:link, a:visited, a:hover, a:active.
Then be sure to link the stylesheet to all pages in your site!
Beth
