Program Help

Well I'm not sure if I'm on the right track or If I way off but this is what I have so far

Code:

#include <stdio.h>
#include <ctype.h>

void step1()
{
    double temp;

    printf("Please enter a the sample temperature in Degrees Kelvin\n");
    scanf("%lf", &temp);

    return;
}

void step2()
{
    double temp;
    char input;

    printf("Do you wish to convert the sample into (C)Celcius or (F)Fahrenheit?\n");
    scanf("%c", &input);

    if (input == 'c'){
        void step3()
    }
    else if (input == 'f'){
         void step4()
    }
         else
         printf("Invalid Option!\n");

    return;
}

void step3()
{
    int cel;
    double temp;

    cel = (temp-273);
    printf("Temperature in Celcius =%lf \n",cel);

}

void step4()
{
    int cel;
    int fah;
    double temp;

    cel = (temp-273);
    fah = (9*cel/5+32);
    printf("Temperature in Farenheit =%lf \n", fah);



int main()
{
    void step1()
    void step2()

}

Basically, I need the program to accept a number (in Kelvin Degrees) then convert it into Farenheit or Celcius. I have all the correct conversions but I'm struggling with the modular programming aspect of it.

What happens when you compile this code?

HINT: It doesn't.

A development process