Step 3: Create the settings.php file
Step 3 in my opinion is the most important!
Prior to running the installation script, you must create a settings.php file and set some permissions.
Your Drupal download comes with a sample configuration file at sites/default /default.settings.php. The default file must be copied and the new file must be given the correct name, settings.php.
Please note: With Drupal 7.x, on some types of shared/local hosting, if PHP and Apache are run by the same user, Drupal will attempt to execute the first three steps for you. If you get errors referring to the "Settings file" during installation, you can perform these steps manually.
Copy the default.settings.php to settings.php.
Do this from the command line (working from the root of the directory containing your Drupal installation) by typing
cp sites/default/default.settings.php sites/default/settings.php.
Please note: Do not simply rename the file. The Drupal installer needs both files.
You should now have a default.settings.php AND a settings.php file in your sites/default directory.
Make the settings file writeable, so that the installer can edit it, type
chmod a+w sites/default/settings.php or
chmod 666 sites/default/settings.php
Both commands have the same effect.
Several FTP tools like Filezilla, Transmit, and Fetch allow you to change file permissions, using a 'file attribute' or 'get info' command. In this case the file permission should be set to 666. If your FTP client has checkboxes for setting permissions, check both the Read and Write boxes for "Owner", "Group", and "Others" (but leave the Execute boxes unchecked).
Please note: Do not forget to change permissions back after you have run the installation script. Those permissions should be:
chmod 644 settings.php
chmod 755 ../default
To let the files directory be created automatically, give the web server write privileges to the sites/default directory.
chmod a+w sites/default