Follow these instructions to install rAthena on Windows OS.
This installation is using Windows 7 as OS, Microsoft Windows Visual Studio 2010 as compiler and IDE, and XAMPP that has MySQL and PHPMyAdmin to work easier
Installing MSysGit as git environment and TortoiseGit its GUI to clone rAthena.
NOTE: If you willing to not update rAthena in future, you can skip this step
MySQL is used as DBMS (since rAthena does not support TXT server anymore) and PHPMyAdmin also with PHP for in one bundle, are very useful!
You can use MySQL Workbench if you don't like PHPMyAdmin.
rAthena need to be compiled before it's used, let's try by using Microsoft Visual Studio 2010.
Before compiling, please be aware of Choosing Packet Version and Knowing core.h Feature.
You can use other IDE or other C/C++ compiler.