Adding Textbox For Users To Input Text Onto JFrame

I need adding a textbox for users to input text onto my JFRame. Also how come the

frame.add(o);

is getting an error under the "add".

Main method class:

import javax.swing.JFrame;
 public class main
{
public static void main(String[] args)
{
JFrame frame = new JFrame();
bot o = new bot();
 
[Code] ......

Other class (this is where I want the textbox to be)

import javax.swing.JTextArea;
import javax.swing.JTextField;
public class bot {
int x;
int y;
JTextField f = new JTextField();
JTextArea a = new JTextArea(30, 50);
}