How to write cascading style sheets

Program 4

<html>
<head><h1>UG COMPUTER SCIENCE</h1>
<link rel="stylesheet" href="style2.css">
</head>
<body>
<center><h2>STUDENT DETAILS</h2>
<table border="1" align="center">
<h3><tr><td>Register No</td><td>13BCS029</td></tr>
<tr><td>Name</td><td>Mani</td></tr>
<tr><td>Branch of study</td><td>B.Sc CS</td></tr><br></h3>
</table><BR><BR>
<table><h2>RESULT DETAILS</h2><BR><BR>
<table border="1" align="center">
<tr><td>Semester </td><td>Subject</td><td>Mark</td><td>Result</td></tr>
<tr><td>IV</td><td>WT</td><td>69</td><td>pass</td></tr>
<tr><td>IV</td><td>Open Source</td><td>88</td><td>pass</td></tr>
<tr><td>IV</td><td>Maths</td><td>90</td><td>pass</td></tr>
</table>
</center>
</body>
</html>

Filename : Style2.css

h1{
color:blue;
font-family="times new roman";
text-align:center;
}
h2{
color:red;
font-family="times new roman";
text-align:center;
}
table{
color:green;
font-family="times new roman";
text-align:center;
table-align="center";
}