Different websites have different needs. The needs of Amazon, Google, and the neighborhood pizza restaurant differ greatly. This is why most no single software can respond to the needs of every client. Drupal was built with this in mind. Drupal comes with a core which can be extended with modules. The core provides essential functions and enables integration and controlled interaction between different modules. Modules can be created by anyone. Modules integrate seamlessly with drupal as long as they are created following drupal guidelines and conventions. Hundreds of really cool drupal modules are available for free on the Internet. Your goal as a beginning drupal user should be to find and install the modules that would allow you to provide the functionality you want to provide to yourself and your users.
Before a module can be used, it must be enabled.
Administer > Site building > modules
Click on the checkbox next to Contact and then click on Save configuration. Once a module is enabled, its settings and other options become visible. In this case, the Contact form link become visible under Site building. Lets create a contact form.
Administer > Site building > Contact Form > Add Category
Fill in the form and hit submit. Repeat this several times, once for each email account that would be receiving emails. Type the following URL in you address bar:
Here you would see a contact form where the category allows you to choose between email accounts. Note that the email addresses are not show and thus cannot be copied by spambots.
Drupal comes with several preinstalled modules such as Contact form we just used. As there are hundreds of modules, most of the modules you would use would have to be downloaded and installed. Modules can be found at http://drupal.org/project/Modules. Suppose we want to download the diff module. Drupal themes and modules are available as zipped tar files. On Unix, you do the following:
$ wget http://the-site/module.tar.gz
$ tar -xzvf module.tar.gz
$ rm module.tar.gz
On windows, download http://www.7-zip.org/. This free tool works with several unix specific zipped files. I have installed cygwin, which allows me to run unix command-line tools on my windows machine.
Once you have extracted the files, you need to upload the folder into the modules folder. I use fireftp to upload files. It is very neat firefox plugin.
Once you have uploaded your files, they should become visible in the list of modules:
Administer > Site building > Modules
Click on the radio button and checkbox to the left of your new module and click on save configuration to enable it.
Before installing a module, you should read its README.txt and INSTALL.txt file. Certain modules conflict with others, and some require special configurations. These small and easy to read files would save you lots of trouble.
To delete a module, just delete its folder from the modules directory.