how to get this CSS work?

%@ Page Title="About Us" Language="C#" MasterPageFile="~/Site.master" AutoEventWireup="true"
    CodeFile="SignUp.aspx.cs" Inherits="About" %>
<asp:Content ID="HeaderContent" runat="server" ContentPlaceHolderID="HeadContent">

<asp:Content ID="BodyContent" runat="server" ContentPlaceHolderID="MainContent">
<!--Content Section -->
<div align="center" class="signup_form_heading">
<h1>Login to Vid Stream</h1>
<p>Lorem Ipsum is simply dummy text of the printing and
typesetting industry.</p>
</div>
<form action="#">
<div align="center" class="signup-form">
<ul>
<li><label>Name:</label><span><input type="text" value="Name" class="txt-field"  onfocus="if(this.value == 'Name') { this.value = ''; }"  önblur="if(this.value == '') { this.value = 'Name'; }" /></span></li>
<li><label>Email:</label><span><input type="text" value="User Name" class="txt-field"  onfocus="if(this.value == 'User Name') { this.value = ''; }"  önblur="if(this.value == '') { this.value = 'User Name'; }" /></span></li>
<li><label>Password:</label><span><input type="password" value="password" class="password" onfocus="if(this.value == 'password') { this.value = ''; }"  önblur="if(this.value == '') { this.value = 'password'; }" /></span></li>
<li><label>Password:</label><span><input type="password" value="password" class="password" onfocus="if(this.value == 'password') { this.value = ''; }"  önblur="if(this.value == '') { this.value = 'password'; }" /></span></li>
<li><div><input type="submit" value="Sign Up" class="signup-btn" /></div></li>
</ul>
</div>
</form>
<br class="clear" />
<!--Content Section End -->

.signup_form_heading {
width:297px;
float:left;
background:url(../images/db-border.gif) repeat-x bottom;
padding-bottom:6px;
margin-bottom:20px;
}
.signup_form_heading h1 {
height:46px;
background:url(../images/login-heading.png) no-repeat left top;
text-indent:-9999px;
margin-bottom:8px;
}
.signup_form_heading p {
line-height:18px;
padding-bottom:12px;
font-family:Arial, Helvetica, sans-serif;
color:#00555a;
}
.signup-form
{
float:none;
width:297px;
padding-top:5px;
}
.signup-form li{
float:left;
width:297px;
padding-bottom:13px;
}
.signup-form li label {
display:block;
float:left;
width:81px;
font-weight:bold;
font-size:12px;
color:#00555a;
font-family:Arial, Helvetica, sans-serif;
line-height:27px;
}
.signup-form li span {
display:block;
float:left;
width:211px;
height:27px;
background:url(../images/bg-input-usr.png) no-repeat left top;
}
.signup-form li span input {
float:left;
width:191px;
height:15px;
font-size:11px;
color:#787979;
border:none;
font-family:Arial, Helvetica, sans-serif;
background:none;
padding:6px 10px;
}
.signup-form li span input.password {
font-size:18px;
}
.signup-form li div {
float:left;
padding-left:81px;
width:211px;
padding-top:5px;
padding-bottom:2px;
}
.signup-form li div label {
font-weight:normal;
width:auto;
font-size:11px;
line-height:15px;
color:#6f6f6f;
width:120px;
}
.signup-form li div label input {
float:left;
margin-right:6px;
width:15px;
height:15px;
line-height:0;
font-size:0;
}
.signup-form li div a {
float:right;
display:block;
width:90px;
text-align:right;
}
.signup-form li div input.login-btn {
float:left;
width:87px;
height:29px;
background:url(../images/btn-login.gif) no-repeat left top;
border:none;
text-indent:-9999px;
line-height:0;
font-size:0;
cursor:pointer;
}