External Resources
Arduino Programming
Start by visiting the most definitive place for information about Arduino at http://www.arduino.cc/. Arduino is an open-source electronics prototyping platform based on flexible, easy-to-use hardware and software.
Download Arduino Software (download the software for Windows, OSX, or Linux)
Arduino Forums (a good place to get some help if you get stuck, but refrain from asking someone else to write your programs)
Links to excellent tutorials and information available at https://sites.google.com/a/umn.edu/me2011/arduino
I have highlighted the ones that I think are most relevant for your project.
Arduino Guide (PDF file) -- read this guide first
Interfacing Devices to the Arduino
Hooking up an LED, a switch and a motor
DC motor, including bi-directional control
Photocell (light sensor)
All about LEDs
Distance sensing with sonar
Temperature sensing
Reading analog signals
Troubleshooting
Links to ITP Physical Computing web page at http://itp.nyu.edu/physcomp/Tutorials/Tutorials
(contains visually detailed, nicely illustrated tutorials on electronics and Arduino programming. All of these are very helpful for your project.)
Components Some of the basic components
Breadboard Setting up a breadboard
Soldering Begining soldering exercise -- soldering a power connector
Electronics Introduction to electronics
Switches Switches
Digital input and output on the Arduino Module
Analog input and output on the Arduino Module