ATMega328P control servo motor speed with potentiometer

Question

I'm trying to develop an application in atmel studio 7.0 which will allow me to control the speed of my servo motor with my potentiometer. Now, the problem is that I don't really know how to do that? Also my servo motor spins around and around instead of going 0 -> 45 -> 90 degrees and then back the same way again. I've managed to do a successfull convertion of analog signals to use, and I've set my admux input channel to 2; also, my pwm channel is 10 for the servo motor. I use an Arduino Uno with Atmega328P processor with 16 000 000 Hz.

Might also say I'm pretty new to the use of PWM, which is why this would be an exciting thing to do.

Heres the code this far:

void initPWM();
void initADC();
uint16_t doConversion(void);

int main(void)
{
    DDRD = 0b11111111;
    DDRB = 0xFF;
    initADC();
    initPWM();

    while (1)
    {
      PORTB = 0b00000100;
      OCR1A=250;   //0 degree
      _delay_ms(2000);

      OCR1A=375;  //45 degree
      _delay_ms(2000);

      OCR1A=500;  //90 degree

      _delay_ms(2000);

      OCR1A = 0;

      _delay_ms(5000);
    }
}

void initPWM(){
   TCCR1A|=(1<<COM1A1)|(1<<COM1B1)|(1<<WGM11);        //NON Inverted PWM
   TCCR1B|=(1<<WGM13)|(1<<WGM12)|(1<<CS11)|(1<<CS10); //PRESCALER=64 MODE 14(FAST PWM)
    ICR1 = 4999 ; // 50 Hz 
}

void initADC(void) {
    // Configure the ADC module
    ADMUX = 0b11000010; //Set channel 2
    // REFS1:0 = 01 -> AVCC as reference,
    // ADLAR = 1 -> Leftadjust
    // MUX4:0 = 00000 -> ADC0 as input
    ADCSRA = 0b10000111;
    //ADEN = 1: enableADC,
    // ADSC = 0: don't start conversion yet
    // ASPS2:0 = 001: pre-scaler= 2
    // ADATE = 0: disable auto trigger,
    // ADIE = 0: disableADC interrupt
}

uint16_t doConversion(void){
    uint16_t result;
    // Start conversion by setting flag ADSC
    ADCSRA |= (1 << ADSC);
    // Wait until conversion is  completed
    while(ADCSRA & (1 << ADSC));
    // Read the all bits, output to PORTB
    result= ADC;
    return result;
}

I used 4999 as the value for ICR1 since I have a 16000000 Hz CPU and use a prescaler of 64.

My servo motors degrees are based on the following: 0 degrees = 1000 microseconds 45 degrees = 1500 microseconds 90 degrees = 2000 microseconds

PORTB is for using the pwm, and the potentiometer is connected to channel 2.

Does anyone know what I did wrong? Or can help me solve/accomplish what I'm trying to do?