Download the codeigniter latest version using the below urls
CodeIgniter Installation Steps
1.Unzip the package.
2.Upload the CodeIgniter folders and files to your server. Normally the index.php file will be at your root.
3.Open the application/config/config.php file with a text editor and set your base URL. If you intend to use encryption or sessions, set your encryption key.
4.If you intend to use a database, open the application/config/database.php file with a text editor and set your database settings.
Normal Directory Structure
project/application project/system project/user_guide project/index.php
Increase Security For Application Folder
Rename The Application Folder
If you wish to increase security by hiding the location of your CodeIgniter files you can rename the system and application folders to something more private. If you do rename them, you must open your main index.php file and set the $system_folder and $application_folder variables at the top of the file with the new name you've chosen.
Rename the directory structure to make it private
project/project_name_application project/project_name_system project/user_guide project/index.php
Now we have to change the '$system_path' and '$application_folder' path.
$application_folder = 'project_name_application'; // on line number 75. Version 2.1.4 $system_path = 'project_name_system'; // on line number 59. Version 2.1.4
For the best security, both the system and any application folders should be placed above web root so that they are not directly accessible via a browser. By default, .htaccess files are included in each folder to help prevent direct access, but it is best to remove them from public access entirely in case the web server configuration changes or doesn't abide by the .htaccess.
After moving them, open your main index.php file and set the $system_folder and $application_folder variables, preferably with a full path, e.g. '/www/myproject/system'.
project_name_application project_name_system project/user_guide project/index.php
Note: Now we have to change the '$system_path' and '$application_folder' path.
$application_folder = '../project_name_application'; // on line number 75. Version 2.1.4 $system_path = '../project_name_system'; // on line number 59. Version 2.1.4