Well, you can use 3 modes for controlling GPIO's
First mode via sysfs user space, this is the simplest mode and you don't to need to know python nor C language.
First read GPIO RaPI WIKI
And GPIO LMK WIKI
Let's take an practical example:
Connect a LED with a resistor (270 or 330 ohm) to pin 37 (GPIOC21) and 39 (GND) and pay attention to the polarity of the LED.
Now calculate the correct numbering index:
GPIOC21 = 64 +21 = 85
export it via sysfs (you need to be root):
linaro@localhost:~$ sudo su
[sudo] password for linaro:
root@localhost:/home/linaro# echo 85 > /sys/class/gpio/export
Set the GPIOC21 pin as output
root@localhost:/home/linaro# echo out > /sys/class/gpio/gpio85/direction
Set the GPIOC21 to 1 (3V3)
root@localhost:/home/linaro# echo 1 > /sys/class/gpio/gpio85/value
Now your LED connected to pin 37 and 39 should light.
Second mode using RaPi.GPIO library, this is a library for python.
You need to know at least a little bit of python for using this library.
An example using the same LED connected to pin 37 and 39 and using the GPIO control example code from the GPIO RaPI WIKI
write this little python program and save it as blinking_gpioc21.py
import RaPi.GPIO as GPIO
PINs = 
for PIN_NUM in range(len(PINs)):
print("Failed to setup GPIO %d", PIN_NUM)
Execute this little program:
root@localhost:/home/linaro# python blinking_gpioc21.py
You should see a blinking LED.
Third mode is using WiringRaPI library, this is a C library.
You need to know at least a little bit of C for using this library.
If you know C then I don't think that you need a tutorial for using this library.
Just look at the examples.