Installing libiowkit.so follows the standard way of

./configure
make
make install

"make install" has to be run as root.

"make" will compile libiowkit.so locally and also compile a test application tests/iowkittest.
"make install" will copy libiowkit.so to /usr/lib and call ldconfig to make it globally accessible.
Also iowkit.h is copied to /usr/include for the same reason.

Installing Java support is explained separately in INSTALL_JAVA.

If the driver for the IO-Warrior has been installed also then you need to unplug and replug
all IO-Warrior devices to allow udev to recognize the devices (if udev is used on your computer).
after that executing tests/iowkittest should blink with all LEDs of the IO-Warrior devices plugged.
From one of the devices (/dev/usb/iowarrior0) the IO pins are read several times.
So if you get a nice blinkenlights the installation was successful.
Read doc/IO-WarriorLibrary.pdf and start writing your own applications.