how would you add

how would you add this code to your .htaccess file

php_value upload_max_filesize 1000M
php_value post_max_size 2000M
php_value memory_limit 3000M
php_value max_execution_time 180
php_value max_input_time 180

I have to add it to the bottom of the file.

when i added to the bottom it crashes my site