Pass parameter from HTML to PHP

[Rong]

Hello, everyone,
I have a very simple question about passing the parameter from the HTML to the PHP.

      Let's say, I have 

<a href="dosomething.php'>20</a>

       How can I pass the number 20 to the "dosomething.php"?

       Thank you in advance!

       Rong

[stuartc1]

<a href="dosomething.php?num=20'>20</a>

where $num will be the variable holding 20 as tha value.