Use BCD Switch to vary Frequency with PIC

I just finished going through a beginner’s book and I've learned the basics but I still have a lot of questions. Well I wanted to see if anyone can help write a code for a PIC that would take a BCD switch input and output the frequency. So for example if I set the BCD switch to 9 it would output 9Khz.

Here's what I've done so far:

#include <htc.h>
#include <pic.h>



//Configuration for PIC16F877 Using HI-TECH C COMPILER

__CONFIG (INTIO & WDTDIS & MCLRDIS & UNPROTECT);
// Internal CLK, Watchdog timer off, MCLR off, Code unprotected

//Variable declarations
char BCD_SWITCH;

void main()
{
//Input from switches

//Initialisation
ADCON0 = 7; // A/D ports off

PORTA = 0x00; // clear all PortA
TRISA = 0xFF; // Make all Port A Inputs

//Infinite Loop
//Loop: While 1
while (1)
{
//Get input from switches on Port A
//Input: PORT A -> SWITCHES
TRISA = TRISA | 0xff;
BCD_SWITCH = PORTA;


//Convert BCD_SWITCH setting to an output frequency(Need Help Here)


}


}