By default, Drupal enforces file-size limits on uploads. Although there is a place in Drupal's File Upload settings to alter the maximum file sizes (/admin/settings/uploads), chances are your PHP settings limit file size to 2MB or so.

Fortunately, it's easy to change. Simply upload a file called php.ini containing these entries to the directory containing drupal :

memory_limit = 50M
upload_max_filesize = 10M
post_max_size = 20M


This will raise the available limit, and you can then change the settings for each Drupal role on the settings page within Drupal:

http://yourdrupalserver.com/admin/settings/uploads