There are two ways how you can help fix errors and add missing information.
1. You can update it on our website. Click on the edit link on the info window on top of the maps display and correct the error. Some modifications require a login to protect the data against vandals. You can see the latest modifications here : http://www.geonames.org/recent-changes.html
2. If you have a lot of modifications you can send me a file with the corrected or missing information (csv or spreadsheed) and I run a batch update.
The export is daily, modifications will be in the dump file on the next day.
Of course I understand the problem of the login to protect the data.
How is possible to have this type of access?
As your reference we manage vacation rentals web site like www.tuscany-villas.it based on locality database.
There is a login link in the top right corner of the web page :
http://www.geonames.org/ (the login link is not available on the forum pages)
Click on the link and then fill out the second form to create an account.