I don't get what you want to do, i guess you want to open link when a button is clicked. You can do this instead of making it button, in fact you must do this (unless you use PHP to open .php pages).
<a href="New_Topic.html">New Topics</a> In css:
padding: 2px; /*So border doesn't sting up with text*/
border: 1px solid black; /*Drawing 1 Pixel, Solid Black colored border */
border-radius:2px; /*Making border's round so it doesn't looks like rectangle (in short making it rounded rectangle) */
/* Some decorations */
/*Some more decorations when hovered */