Need help with letter counter program

Alright so I have my code and my methods setup on how i want the program to execute but im still having a little difficulties. The object of the program is to counts the frequencies of alphabet letters in a given file and records the letters and frequencies in another given file. The array is to save the letters and another array to save their frequencies, and a letter and its frequency should have the same index, i.e., letter 'A' has index 0 for both arrays. I have included comments.

[CODE]

import java.io.FileNotFoundException;
import java.io.IOException;
import java.io.PrintWriter;

public class LetterCounter {

/**
* The size of each array is 26 as there are 26 letters in English alphabet.
*
* @param setOfLetter the array to save the alphabet letters
* @param freqOfLetters the array to save frequencies of letters
* @param maxFreqIndex the array index with the maximum frequency
*/
static final int LENGTH = 26;
char setOfLetters[] = new char[LENGTH];
int freqOfLetters[] = new int[LENGTH];
int maxFreqIndex;

/**
* This method return true if ch is in [a-z] or [A-Z]
* @param ch the input character
* @return true if ch is in the range; false otherwise
*/
protected boolean isLetter(char ch) {

if ((ch >= 'a' && ch <= 'z') || (ch >= 'A' && ch <= 'Z')) {
return true;
}
else
{
return false;
}

}

/**
* this method find the index of character ch in the arrays.
* The index is calculated by Character.toUpperCase(ch) - 'A'
*
* @param ch the input character
* @return the array index of character ch
*/

protected int indexLetter(char ch) {
for (int i = 0; i < setOfLetters.length; i++)
if (setOfLetters[i] == ch) {
//return ch;
maxFreqIndex++;
}
return Character.toUpperCase(ch);
}

/**
* This method initializes both arrays. elements in freqOfletters are set to zero,
* and elements in setOfLetters are set to capital letters
*
*/
protected void initFreqs() {

//TODO

}

/**
* this method find the array index with the maximum frequency in an array
* @param values an array of ints
* @return the index with maximum value
*/
protected int findIndexOfMax(int values[]) {
return maxFreqIndex; // find the index of the character with max frequency

//TODO

}

/**
* This method reads character by character from the input file, check if each character is a letter. For letters, it
* increments the frequencies in the array freqOfLetters.
* <p>
* This method also
* @param inFileName the file to read from
* @throws IOException
*/
public void count(String inFileName) throws IOException {

//TODO

}

/**
* This method prints the results to the output file.
* @param outFileName the file to write to
* @throws IOException
*/
public void printFrequencies(String outFileName) throws IOException {

//TODO

}

/**
* This is the driver. It instantiate a LetterCounter object and call count and printFrequencies methods.
* @param args
*/
public static void main(String[] args) {
// TODO Auto-generated method stub
if(args.length != 2){
System.out.println("usage: " + LetterCounter.class.getSimpleName() + " input_file_name output_file_name");
System.exit(-1);
}
LetterCounter c1 = new LetterCounter();
try {
c1.count(args[0]);
c1.printFrequencies(args[1]);
} catch (FileNotFoundException e) {
// TODO Auto-generated catch block
e.printStackTrace();
} catch (IOException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
}
}

[CODE]