What do you need to know exactly?
From what I remember from high school though, plants use the carbon in the atmosphere to do the photosynthesis. The organic carbon then go in the ground or is eaten by animals and then get back into the atmosphere via the organisms respiration. However, I believe the oceans also have their roles in it since they absorb carbon and then reject it later when they are oxygenated (But I can't clearly remember the current process carbon is going through once in the water). Industries are also implicated in the process since they create carbon emissions that will later be used for photosynthesis.
I'm not sure if this is the whole detailed infos you are looking for since I haven't studied the whole process, but I remember seeing it in class a few years ago.
I hope this can help a little.
Maki (05-26-2013)
Carbon cycle is basically the cycle of which carbon is circulated throughout the earth. Mostly it involves the atmosphere, biosphere, soil and the oceans. Carbon on earth's atmosphere has two main forms: Carbon Dioxide which is mostly produced by living things and Methane, both of these gases absorb and retain heat, causing the greenhouse effect. Plants and trees absorb the carbon dioxide through photosynthesis resulting into the return of carbon into the biosphere. Soil respiration also contributes to the release of carbon dioxide. Carbon Dioxide also dissolves in the ocean, this forms carbonic acid(carbonated water), which contribute to the ocean acidity. Carbon in the ocean is absorb by living organism through photosynthesis, thus the cycle. This is the natural carbon cycle.
Although with human influence, production of carbon dioxide has increased, burning of fossil fuels contributes directly into the production of carbon dioxide, air pollution and deforestation also affect the plants and trees, resulting into slower plant productivity.