How do I theme a webform? I am in need to theme webform in D7.

How can I do that ?

In the search I've come to know that by using web-form-nid.tpl.php we are able to theme a drupal individual form.

Could any one guide me in this case to theme a webform.
You can theme a individual webform using webform-form-nid.tpl.php.

For example if our webform node id is 7 , create a template file namely webform-form-7.tpl.php and place it in your theme folder. Clear site cache.

Do a print_r($form); to see all the elements. Then render each elements in file within your html elements.

&lt;li&gt;
    &lt;?php print drupal_render($form['submitted']['name']); ?&gt;
&lt;/li&gt;


As  @Patrick Kenny said read the theming.txt, it explain all aspects of theming a webform