Before asking such kind of Questions Please google it first.. You will get better anwers there itself...
Here is an example....
Place below code inside
tag of your page..
<style type="text/css">
#div1
{
height: 100px;
width: 100px;
background-color: Orange;
border: solid 5px Silver;
border-radius: 10px;
margin: 5px;
}
</style>
Place this inside
tag...
<div id="div1">
</div>
See the outcome of above code... Hope you got it...