First, download CUBRID PHP or PDO Driver for Windows. You will be given options to select your system architecture, PHP version, and driver type (PHP/PDO).
Additionally, you can choose whether to download NTS (Non-thread-safe) or TS (thread safe). If you do not know which version you need, you can go with NTS version. For detailed explanation of these terms, read Stackoverflow answer.
Another option will allow you to choose VC6 (Visual Studio 6) version or VC9 (Visual Studio 2008).
If you are using PHP with Apache 1 or Apache2 from apache.org you need to use the VC6 versions of PHP. VC6 Versions are compiled with the legacy Visual Studio 6 compiler.
If you are using PHP with IIS you should use the VC9 versions of PHP. VC9 Versions are compiled with the Visual Studio 2008 compiler and have improvements in performance and stability. The VC9 versions require you to have the Microsoft 2008 C++ Runtime (x86) or the Microsoft 2008 C++ Runtime (x64) installed. Do NOT use VC9 version with apache.org binaries.
If you are downloading PHP driver, you will see php_cubrid.dll file, otherwise php_pdo_cubrid.dll for PDO driver.
Edit php.ini (C:\Program Files\PHP\php.ini) and add the following two lines at the end of the php.ini file.
or for PDO:
[PHP_PDO_CUBRID] extension = php_pdo_cubrid.dll