The links below should help you out in your research. There are general links that address all the organs together and there are some specific sites for individual organs. Please make sure that you do NOT copy any information word for word. All information written down should be rewritten in your own words.
Body Thinkquest (loads of information)
The Heart -- An easy-to-read, but descriptive outline of the activities of the heart, can be found here. A basic diagram is also provided.
Kidneys -- A clear, basic diagram, accessible glossary for difficult terms, and an excellent description of the kidneys' activities, can all be found at this site.
The Brain -- A general diagram and description of the brain can be found here.
The Lungs -- An in-depth description of the role of the lungs in the respiratory system is given in this site. A good description of a lung's structure, and a basic diagram are included as well.