New to Java

Hi, I have an exam Tuesday and an assignment Ive done before is to draw a chessboard pattern, but a past question has been to draw a grid pattern with red horizontal lines and blue vertical ones.

It must display an input dialog asking the user how many lines to draw along each side and the pattern should size itself to fit exactly with the applet area.

It says to use setColor(Color c) and fillRect(x1,y1,x2,y2): draws lines between (x1, y1) and (x2,y2)

Here's my code for the chessboard:

import java.awt.*;
import java.applet.*;

public class Q2_chessboard extends Applet {
	public void paint(Graphics g) 
	{

		int row, column, x, y;
		
		//for every row on the board
		for (row = 0;  row < 8;  row++ ) 
		{
			//for every column on the board
			for (column = 0;  column < 8;  column++) 
			{
				//Coordinates
				x = column * 20;
				y = row * 20;
				
				//square is red if row and col are either both even or both odd.
				if ( (row % 2) == (column % 2) ) 
					g.setColor(Color.red);
				
				else
					g.setColor(Color.black);
				g.fillRect(x, y, 20, 20);
			} 
		} 
	}
}

But Ive tried for ages and cant turn this code into the code needed for the past question.

I know I have to use:

		//Gets size of Applet
		int appletHeight = getSize().height;
		int appletWidth = getSize().width;

But cant wrap my head around it where to use it.

I had replaced the numerical values of row and column with

		input = JOptionPane.showInputDialog("Enter number lines to draw on each side:");
		lines = Integer.parseInt(input);

but it came asked twice and I couldnt expand the applet without it asking for input again.