<?php phpinfo(); ?>
and save the file as say phpinfo.php then go to this page in a web browser.
Near the top of the page you will see a section that says configuration file path. If this is set to a directory you will need to create a php.ini file in this directory to be able to change any settings. If it is a file then this is the file you need to change settings in.
To increase the maximum file size, you will need to adjust the upload_max_filesize setting. Depending on how much you change this it may also be necessary to increase the post_max_size setting.
After these changes you will have to restart your web server for the changes to take effect.
Finally if you are running Apache you may need to find a setting in Apache's configuration files (usually httpd.conf) that sets the LimitRequestBody to allow the increase. As far as I am aware this is only set by default with Apache2 under Fedora but if the previous changes don't help it might be worth checking this out.
