Save the downloaded file. Open a terminal and give the following command:
The exact file name varies depending on your operating system. If you have Qt environment correctly set up, the installer will automatically launch Into Demo when finished. If you installed Qt SDK to the default location, Into should be able to find it. Otherwise set the QTDIR environment variable correspondingly.
The downloaded file is an installable software package. Open it in software installer.
The downloaded file is an executable file. Run the installer by double-clicking it in the download window.
If you downloaded Qt sources (not the binary SDK), you need to compile and install Qt before Into can work. Be prepared that this takes a whole lot of time. Once you have unpacked the Qt source package, give these commands in a terminal:
cd qt-install-dir ./configure make && make install
Depending on your system set-up you may need to install some additional development packages before configuring Qt. On Debian/Ubuntu this is usually a good beginning:
sudo apt-get install libpng12-dev libfreetype6-dev libsm-dev libxrender-dev \ libfontconfig-dev libxext-dev libglib2.0-dev libxi-dev libxrandr-dev