1:nano /etc/php5/apache2/php.ini
you can find your php.ini location by uploading a file called phpinfo.php with the following contents<?php phpinfo();?>
and access it by visiting yourdomain.com/phpinfo.php ,you will see the results
2:change the desired value to upload_max_filesize and post_max_size such as : upload_max_filesize = 200M post_max_size = 300M then it will become 200M.
3:restart your apache