Hi Guillaume!
Welcome to the oVirt community! I'm sorry to hear you're having problems.
The node project [1] isn't really intended to be used as a stand-alone product. It's purpose is to provide a minimal host environment that's managed by the oVirt engine, which is the heart of the oVirt project. I recommend looking at the deployment options documentation [2] and the quick start guide [3]. They will help you with getting started. If you have any questions about what you see there or get stuck somewhere along the line, we'll be here to help. =)
Best regards,