I am trying to write a program that calculates the price when the checkboxes
are selected and the calculate button is pressed.
Now I am not sure how to code the part where you click the box and the price
of that item appears. Any suggestions?

Here is what I have now:

import java.awt.*; //Abstract Window Toolkit (AWT) for creating
                    //painting graphics, interfaces and images
import java.applet.*; //gives the classes for an applet to create and
                    //communicate in applet context
import java.awt.event.*; //gives classes and interface for different
                    //types of events from the AWT
import java.text.DecimalFormat; //this class formats decimal numbers

public class PetsApplet extends Applet implements ActionListener
{
    //labels declared
    Label welcomeLabel = new Label ("Welcome to the Pet Clinic");
    Label price = new Label("The total price is $0");
    Label current = new Label("The current price is $0");
    Label serLabel = new Label("Select the service:");

    //string text declared
    String currentString = new String();
    String priceString = new String();

    //checkboxes identified
    Checkbox officeBox = new Checkbox("Office Visits $10");
    Checkbox vacBox = new Checkbox("Vaccination $25");
    Checkbox xrayBox = new Checkbox("X-Rays $40");
    Checkbox hosBox = new Checkbox("Hospitalization $100");
    Checkbox denBox = new Checkbox("Dentistry $50");
    Checkbox labBox = new Checkbox("Laboratory Work $30");
    Checkbox heartBox = new Checkbox("Heartworm Prevention $35");
    Checkbox boardBox = new Checkbox("Boarding $5");
    Checkbox preBox = new Checkbox("Prescription $55");
    Button calcButton = new Button ("Calculate");
    Label outputLabel = new Label("Click the calculate button for total price");

    //price variables of the services declared along with the totalPrice
    int totalPrice = 0;
    int officeBoxPrice = 10, vacBoxPrice = 25, xrayBoxPrice = 40, hosBoxPrice =
100;
    int denBoxPrice = 50, labBoxPrice = 30, heartBoxPrice = 35, boardBoxPrice =
5, preBoxPrice = 55;

    public void init()
    {
        //adds all the components to the applet interface
        setBackground (Color.blue);
        add(welcomeLabel);
        add(serLabel);
        add(officeBox);
        add(vacBox);
        add(xrayBox);
        add(hosBox);
        add(denBox);
        add(labBox);
        add(heartBox);
        add(boardBox);
        add(preBox);
        add(current);
        add(calcButton);
        calcButton.addActionListener(this);
        add(outputLabel);
        add(price);
    }

    public void actionPerformed(ActionEvent e)
    {
            //the current price statement is identified
            if (officeBox.getState())

            currentString = ("The current price is $"+ Integer.toString
(officeBoxPrice));

            if (vacBox.getState())

            currentString = ("The current price is $"+ Integer.toString (vacBoxPrice))
;

            if (xrayBox.getState())

            currentString = ("The current price is $"+ Integer.toString (xrayBoxPrice))
;

            if (hosBox.getState())

            currentString = ("The current price is $"+ Integer.toString (hosBoxPrice))
;

            if (denBox.getState())

            currentString = ("The current price is $"+ Integer.toString (denBoxPrice))
;

            if (labBox.getState())

            currentString = ("The current price is $"+ Integer.toString (labBoxPrice))
;

            if (heartBox.getState())

            currentString = ("The current price is $"+ Integer.toString (heartBoxPrice)
);

            if (boardBox.getState())

            currentString = ("The current price is $"+ Integer.toString (boardBoxPrice)
);

            if (preBox.getState())

            currentString = ("The current price is $"+ Integer.toString (preBoxPrice))
;

            //the text is set equal to currentString
            current.setText (currentString);

            //total price is calculated
            totalPrice = 0;

                if (officeBox.getState())
                totalPrice += officeBoxPrice;

                if (vacBox.getState())
                totalPrice += vacBoxPrice;

                if (xrayBox.getState())
                totalPrice += xrayBoxPrice;

                if (hosBox.getState())
                totalPrice += hosBoxPrice;

                if (denBox.getState())
                totalPrice += denBoxPrice;

                if (labBox.getState())
                totalPrice += labBoxPrice;

                if (heartBox.getState())
                totalPrice += heartBoxPrice;

                if (boardBox.getState())
                totalPrice += boardBoxPrice;

                if (preBox.getState())
                totalPrice += preBoxPrice;

                //output statement for total price is identified
                priceString = ("The total price is $" + Integer.toString (totalPrice));
                price.setText (priceString);

                //statements to clear the fields after the calculate button is clicked
                officeBox.setState(false);
                vacBox.setState(false);
                xrayBox.setState(false);
                hosBox.setState(false);
                denBox.setState(false);
                labBox.setState(false);
                heartBox.setState(false);
                boardBox.setState(false);
                preBox.setState(false);

    }
}