error:method in class cannot be applied to given types? cannot be seen

I am making a hangman game, this is the part of my code where all the problems are:

    	//play method
        private void play() throws IOException
    	{
			guess(alphabet);

			usedLetters(letterUsed);

			do{
				centreln("You have already guessed this " + alphabet + " and the others listed above.");
    			guess();
    		} while (letterUsed == true);//will keep asking until letter was not used

    		if (letterUsed == false)
    		{
    			life--;
    			underWord();
    		} //only if the letter was not used, it will be checked for in the current word trying to be solved

    		if (life == 0)
    		{
    			checkWord(currentWord[] , checkLetter[]);
    		}
    	}//End of play method

//------------------------------------------------------------------------------------------------------------------------------

	//maskWord method to return the word with all characters not in letters replaced by _'s
	private void underWord(char currentWord[] , char checkLetter[]) throws IOException //add parameters what it recieves
	{

        for (int i = 0; i<currentWord.length; i++) {
           for (int index = 0; index<checkLetter.length; index++){
           		if (used.contains(currentWord.charAt(i)))
            	{
                	checkLetter[index] =  currentWord.charAt(i);
            	}

            	else
            	{
            		checkLetter[index] = '_';
            	}
       	   }
		}
        for (int i = 0; i < checkLetter.length; i++)
        {
        	System.out.println(checkLetter[i]);
        }
    }//End of maskWord method

//------------------------------------------------------------------------------------------------------------------------------

    //guess method to ask for user's guess
    private void guess(char used[]) throws IOException//add parameters what it recieves
    {
    	centreln("Guess a letter in this 5-letter word: ");
    	alphabet = kb.readline().charAt[0];
    	used[dataSize] = alphabet;
    	//adds guess to used letters array

    }//End of guess method

//------------------------------------------------------------------------------------------------------------------------------

    //usedLetters method to check if user's guess has already been guessed
    private boolean usedLetters(char used[]) throws IOException//add parameters what it recieves
    {
        boolean letterUsed = false;
        for(int x=0; x<used.length; x++)
        {
            if(alphabet == used[x])
            {
                letterUsed = true;
            }
            else
            {
                letterUsed = false;
            }
         }
         return letterUsed;
        for (int index = 0; index < used.length; index++)
		System.out.println(used[index]);
		//Or could i just do centreln(usedAlphabet)
    }//End of usedLetters method

//------------------------------------------------------------------------------------------------------------------------------

    //checkWord method to see if the user has got the correct word
    private void checkWord() throws IOException
    {
        for(int x=0; x<currentWord.length; x++)
        {
           	if(checkLetter.equals(currentWord))
            {
            	centreln("HUZZAH! You have guessed the word!");
            	centreln("You have completed this game of hangman.");
            	menu();
            }

            {
                centreln("You have run out of guesses!");
                centreln("The word was:");
                	for (int index = 0; index < currentWord.length; index++)
                	{
                		System.out.print(currentWord[index]);
                	}
				menu();
        	}
    	}
    }//End of checkWord method
}

//------------------------------------------------------------------------------------------------------------------------------

So I come up with these errors:

C:\Users\HOME\Documents\JCreator LE\MyProjects\twoHangman\src\twoHangman.java:256: error: method guess in class twoHangman cannot be applied to given types;
guess(alphabet);
^
required: char[]
found: char
reason: actual argument char cannot be converted to char[] by method invocation conversion
C:\Users\HOME\Documents\JCreator LE\MyProjects\twoHangman\src\twoHangman.java:258: error: method usedLetters in class twoHangman cannot be applied to given types;
usedLetters(letterUsed);
^

required: char[]
found: boolean
reason: actual argument boolean cannot be converted to char[] by method invocation conversion
C:\Users\HOME\Documents\JCreator LE\MyProjects\twoHangman\src\twoHangman.java:262: error: method guess in class twoHangman cannot be applied to given types;
guess();
^
required: char[]
found: no arguments
reason: actual and formal argument lists differ in length
C:\Users\HOME\Documents\JCreator LE\MyProjects\twoHangman\src\twoHangman.java:268: error: method underWord in class twoHangman cannot be applied to given types;
underWord();
^

I am not sure what is wrong...It would be appreciated if someone would help!