Permissions
One simple way to protect yourself is to ensure that you have the permissions set on your files and directories. The following settings are the recommended permissions:
.htaccess............644
configuration.php... 644
Directories .........755
Files............... 644
While these are recommendations, your particular needs may be different and you should adjust accordingly.
Note
For a detailed explanation of permissions visit this link on the Joomla.org site:
User Management
When you set up your site, there are several different methods to manage users and their permissions. The permutations are numerous and I would suggest you to pick up a copy of Barrie North's book:
The Joomla Admin Manual: A Step by Step Guide to a Successful Website
Or
Joomla! A User's Guide
You can find both of these at joomlabook.com or Amazon.com
Later, we are going to learn about tools to help you post-install. However, if you have taken these steps, you are doing very well indeed.