[quote user="jayadev jayaram"]i would like to get a code[/quote]
I would also like to get a code I need. Thing is that I have to create it myself.
[quote user="jayadev jayaram"]create an ambient led system on the breadboard which gets brighter as the room brightness decreases. [/quote]
You need light sensor which you read using ADC. Also you need LED drive using PWM. Typical light sensor ir photodiode, however generic LED can be used too: http://www.instructables.com/id/LEDs-as-light-sensors/
PWM is not that hard - check Source Code Examples, look for timer PWM example.