how to provide button style to an html actionlink

This goes inside your CSS file:

.roundedButton {
    font-family: Verdana, Helvetica, Arial, sans-serif;
    font-size: 12px;

    color: #181818;
    color: rgba(0,0,0,0.4);
    width: 65px;

    padding: 8px 12px;
    border: none;
    outline:none;
    outline:0;

    -moz-border-radius: 2px;
    -webkit-border-radius: 2px;
    border-radius: 2px;

    -moz-box-shadow: 0px 1px 3px rgba(0,0,0,0.4);
    -webkit-box-shadow: 0px 1px 3px rgba(0,0,0,0.4);
    box-shadow: 0px 1px 3px rgba(0,0,0,0.8);
}

I believe this may be what you're after.

Html.ActionLink("ActionLink Text", null, new { @class="roundedButton"})