To get started with RPi.GPIO, it would be worthwhile reading the examples in the project wiki (link above).
Note that this module is unsuitable for real-time or timing critical applications. This is because you can not predict when Python will be busy garbage collecting. It also runs under the Linux kernel which is not suitable for real time applications - it is multitasking O/S and another process may be given priority over the CPU, causing jitter in your program. If you are after true real-time performance and predictability, buy yourself an Arduino! (see http://www.arduino.cc )
Note that the current release does not support SPI, I2C, 1-wire or serial functionality on the RPi yet. This is planned for the near future - watch this space!