Carbon dioxide gas is taken up through openings in the leaves called stomata. The old saying about talking to your plants makes them grow better really is somewhat true -- when you expel air you breathe carbon dioxide back into the environment. If you are standing close to a plant, it makes their job easier to trap enough gas.
Water is mainly absorbed through the soil and into the root system. Water then travels up the roots and into the stems and leaves of the rest of the tree. Because of this rising up action (generally called the cohesion-tension theory), water can escape through the stomata on the leaves. For plants that live in an arid environment, they only open their stomata at night to minimize water lose.
Light-dependent reactions are the first parts of the Photosynthesis process. They take place in chloroplast structures called thylakoid stacks or granum. These reactions utilize water and light to help break down electrons and other elements for energy to be used in the light-independent reactions. Light is absorbed by pigment molecules called chlorophyll, and to a lesser extent carotenoids. Chlorophyll absorbs blue and red wavelengths best, but absorbs green the least -- the reflected green wavelength gives leaves their color.
There are two photosystems that employ chlorophyll to absorb light: photosystem I and photosystem II. Photosystem II is actually the first reaction that takes place (it's called photosystem II because it was discovered second). While these systems utilize light and water, oxygen is released as a by-product back into the atmosphere.
The light-independent reactions, also called the Calvin cycle, take the products of photosystems I and II, as well as the carbon dioxide taken up by the plant, and use them to synthesize sugars and other organic compounds needed. These reactions also take place in the chloroplast, but in the space surrounding the thylakoid stacks called stroma.
Each turn of the Calvin cycle uses one carbon dioxide molecule, and it takes six turns to make a glucose (sugar) molecule. Once the products are made, they are transported to other parts of the plant, such as the roots, stems and trunk, which the cells will either use in their own reactions or store for later use.
While this cycle is called the light-independent reactions, the name can be misleading: the cycle still utilizes light, just indirectly through the light-dependent reactions.