Put very simply, the four noble truths are the truths of: Suffering, the origin of suffering, the end of suffering and the road to the end of suffering. These are considered as steps on a journey.
The first step is finding out the problem, sickness or suffering. The second is finding what causes it. The third step is understanding that the problem can be solved or the sickness cured, and the fourth, the path to enlightenment, is the actions you take in order to solve the problem.
In Buddhism, the root of all suffering is considered the same; desire or attachment to worldly things. The basis of this is either greed, ignorance, hate or a combination of them. The cure is to free yourself from earthly needs and desires, and this should be achieved by right thinking, right actions and other steps.
You can get an overview of these ideas here.