HTML and PHP are very different. HTML is used for your browser to pick up on read-able code and form objects using it, which is what you see on your screen. PHP is a server addon designed to allow dynamic content. It basically is a web server language, in a syntax similar to C.
PHP 'echos' or 'prints' HTML code using a variety a formulas to decide what HTML for the web server to load into your browser. A simple example of this is check the day of the week. A simple peice of PHP code can be used to check the date:
code:
<?PHP
$date = date('D');
if ($date == 'Mon')
{
echo "It's monday";
}
else
{
echo "It is not Monday";
}
?>
Of course you can't do this with HTML. PHP is something needed to be installed on a server, whereas HTML code is something all up to your browser. The 'echo' used shows the HTML code like you would normally, but the PHP checks to see what code should be echoed
Edit: There is no such thing as converting HTML to PHP, and your best chance is to post your HTML page and explain what is not working
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