There are some installation packages for Linux: One for Debian based Linux distributions and one for Fedora based distributions.
All packages you can download from the qStopMotion download site.
If you use an other distribution please build qStopMotion from the sources.
The package ffmpeg must be installed on Fedora and CentOS, to create a video from the single images. You can read the instructions on the FAQ page.
After the installation of the required software packages you can download the windows installer from the qStopMotion download site.