Inserting Google ads

I am contemplating using the Tempera theme on my web site. I like all the features and layout options. One problem I am having is inserting the code for my Google ads, particularly on the main page. The following code is supposed to be inserted on the index.php page.

<?php if(function_exists(“wp_template_ad”)) { wp_template_ad(“3”); } ?>

When I insert it on the Tempera theme, I get a line error. Any help would be appreciated. Thanks.