It sounds like homework... If it is, you need to do it yourself. No point in having a degree if you don't know how things work (would you trust an engineer to build the home you live in, if you knew they got other people to do their assignments for them?).
Regarding the first post, run the command 'gpio readall' to find the pin you're trying to use, as referenced here:
http://wiringpi.com/the-gpio-utility/
Since the MCP2515 CAN device uses SPI, you can find out how to set that up here:
http://wiringpi.com/reference/spi-library/
The RS485 might be a different issue (voltage issues, from what I've read), but you should be able to use a USB to RS485 adapter for that (or an I2C board).
Keep in mind that the Pi uses 3.3V logic, not 5V. If you use 5V, you will kill the Pi. You can get adapter boards that switch up to 5V and back down to 3.3V, relatively cheap.
[EDIT]
Also, make sure you have a resistor in the LED circuit, otherwise you will kill the LED.