First you need an Operating System which supports cluster computing. It could be one of the Linux distributions like Scientific Linux or it may be a version of Windows Server (have not tried it yet).
The other component you need is your software let it be either an engineering simulation software or an image renderer or something else. The software you want to use and the license you have for it must be be capable of handling job distribution among several computers.
Some of the software tools like one of our Fluid Dynamics simulation tools can only do distributed computing if you have the necessary license to run such calculations.
Some of the open source codes in the fluid dynamics world like OpenFOAM as an example can run distributed computing without any further licensing requirements.