LEDs , buttons, IOs, help me

hello my new friends!
I'm new to the world of the embedded programming . but I'm an expert Qt
developer for desktop applications. Now i have bought a mini2440 friendly
arm board since last week and i ran my hello world program with my board
wow :) . but i don't have any idea how to communicate with outputs or
inputs .for example how can i send my outputs to the LEDs? or buzzer or or
serial port or how can i get the inputs from buttons ?
thanks for your helps
My English writing skill is horrible :) isn't it?

i've found this code for leds but it is for TQ2440. can some body help me?
void beep::beep_init()
{
int temp = beep_slider->value( );
//把滑块（微调&#
24320;关）的值赋给
temp 变量
fd = open("/dev/EmbedSky-Beep", O_RDWR); //打开设备
if (fd < 0)
{
perror("open device EmbedSky-BEEP");
close();
}
printf("times = %d \n",temp);
ioctl(fd, temp, 4);
//&#22240;&#20026;&#26377;&#21021;&#22987;&#20540;&#
65292;&#25152;&#20197;&#21021;&#22987;&#21270;&#23436;&a
mp;#27605;&#34562;&#40483;&#22120;&#23601;&#25353;&#2903
1;&#21021;&#20540;&#40483;&#21483;
//
qWarning( "beep::beep_init(): Not implemented yet!" );
}
void beep::beep_set()
{
int temp = beep_slider->value( );
printf("times = %d \n",temp);
ioctl(fd, temp, 4);
//
qWarning( "beep::beep_set(): Not implemented yet!" );
}

GPIO: "/sys/class/gpio/gpio<number>/value"
LED: "/sys/class/leds/<led name>/brightness"
Buttons: "/dev/input/event0"
Buzzer: Like GPIO

thanks a lot for your reply but what are these ? :) can u give a reference?
for other concepts too !
thanks a lot again

GPIO: Read kernel's Documentation/gpio.txt
Buttons: Read kernel's Documentation/input/input.txt
LED: Read kernel's Documentation/leds/leds-class.txt