Let's start the overview of Photosynthesis with the Bozeman Science video, Photosynthesis, https://youtu.be/g78utcLQrJ4?list=PL7A750281106CD067
Alternative you can watch the Crash Course Photosynthesis video, https://youtu.be/sQK3Yr4Sc_k?list=PL3EED4C1D684D3ADF
Photosynthetic organisms are producers, this means they make their own source of chemical energy. From the video(s) you should have picked up that chlorophyll is the molecule that absorbs light energy. In plants, chlorophyll is found in the chloroplast organelle.
There are two parts of the chloroplast involved in photosynthesis, the grana or thylakoids and the stroma.
First let's look at the light-dependent reactions. These take place in the thylakoids, and require water and sunlight. The chlorophyll absorbs the light energy, which is transferred along thylakoid membrane to the light-dependent reactions, and oxygen is released.
The equation for this process is:
6CO2 + 6H2O --> C6H12O6 + 6O2
Or you might remember this as:
Carbon Dioxide + Water --> Sugar + Oxygen