Can someone explain ATP and ADP to me in way that I can understand

I have a big test in Honors Biology on Tuesday and i really need help because the textbook is really confusing the way it explains it. The two chapters are about photosynthesis and cellular respiration. Thanx! C:

The processes of photosynthesis and cell respiration both create ATP, or energy. ATP just means that there are three phosphates instead of two. ADP only has two phosphates. In order for your body to use ADP, it needs another phosphate. Photosynthesis and cell respiration are what add this phosphate. They use three cycles in order to do this. The third cycle is what creates the most ATP. When ATP is used, it becomes ADP again and re-enters the cycles.

In case you didn't already know, plants do go through cell respiration, but first they have to go through photosynthesis. Also, photosynthesis uses NADP/NADPH. Cell respiration uses NAP/NAPH.

I could do that but I would do you a much bigger favor by telling you a fool-proof way for you to get an A.
The first tip is to send you to khanacademy.org which will be a huge benefit for your learning in other classes too, but scroll down to their Science section and click on Biology. Then click on Cellular Respiration and the ATP video free.
Any terms that you don't completely understand go to wikipedia and read about them, then go to google "searchterm animation"
In other words, put the term you're in question about in the space that says searchterm, followed by the word animation.
If you do this with each term that will be on the test you will be prepared.
Bestoflucktoyou

here's a link to a short video that shows how ATP synthase combines ADP and Phosphate ions to create ATP.

ATP - Adenosine triphosphate, the universal energy currency of all known living organisms.

ADP- Adenosine diphosphate, an important part of photosynthesis and glycolysis.