In a bluehost subdomain I want to use a different php version. Default is 5.4, I want to use 5.6. According to this link all I have to do is add a .htaccess file
# Use PHP5.6 as default
AddHandler application/x-httpd-phpbeta .php
But the php is not running, so no page is showing.
You mentioned it is a subdomain. Are you using a free hosting service.
All the server options wont be available for a free hosting service.
Check which version of php is installed using,
<?php phpinfo(); ?>
If the website page is blank, reason could be, errors might have been disabled by default. So enable php errors and check. Also, check server error log.