Did you get it on disk or from an online service?
If on disk, just startup the disk and run the install program. It will take care of putting itself where it needs to go. (Which is inside the CIV folder) Check the version number. If it isn't 2.13 (the last one), then you will want to download the 2.13 patch from the Forum's download page. If you need to do that, the download will have an installer as well.
If you used an online service, the service should furnish install instructions. They all do it differently and are non-standard compared to the disk source.