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.