If you can tell me (e.g., a specific gaming forum or website) or what kind of files are inside it (e.g., .iff files), I can give you more specific, direct instructions on how to install it.
Note: If the file is password-protected, the source where you downloaded it from will usually provide the password. 3. Installation/Usage
You need a program to extract .rar files. The most popular ones are: WinRAR (Official tool for .rar files) 7-Zip (Free and open-source)