Is there a place PHP can write to or one onto which to upload a file and use PHP to read it?
PHP is configured to be restrictive on the personal web servers in order to ensure a certain level of security and privacy for our users. Currently, you can only access files that you own in your AFS space and a few other select locations.
In order to allow PHP to write to a directory, you will need to alter the AFS permissions on the directory. You will need to give the personalweb group rlidwk permissions in the directory that you wish to be writeable. There are instructions for using the Network Identity Manager to make the necessary AFS permission changes. You can view them here.