Ajax requests for php queries

Ajax requests for php queries

I am using cache plugin for wordpress website, Well I have few questions,
actually I don't want plugin to cache the following php codes (the code is
for ratings, download counts and page views.
<?php if(function_exists('the_ratings')) { the_ratings(); } ?>
<?php setPostViews($post->ID); ?>
<?php echo getDownloadCounter(get_the_ID()); ?>
The owner of plugin suggested to use Ajax requests.
Can anybody please how to adjust the above code in ajax? I am new to such
things.
Thanks.