link to an external web page

Hello,

In a page of my site I have a form where I collect data, including the web page. After I gather this information I want to display them.
Lets say $webpage is the variable that store the web page I collected.

<h4><?php echo __(‘Pagina web:);?>
” target=’_blank’><?php echo $web;?></h4>
If $webpage == https://www.google.com I want to open that page, but the code above try to open something like this localhost/mysite/www.google.com, which doesn’t exists. $webpage is somehow relative to mysite. What to do to fix this?
Thank you.