java.lang.ClassNotFoundException: oracle.jdbc.driver.OracleDriver

I wrote a Java Servlet program but when I run it, it was showing the Exception

java.lang.ClassNotFoundException: oracle.jdbc.driver.OracleDriver

My code is

package skypark;

import java.io.*;
import javax.servlet.*;
import java.text.*;
import javax.servlet.http.*;
import java.sql.*;
import java.sql.Date;

public class Registration extends HttpServlet {

    private static final long serialVersionUID = 1L;

    public static Connection prepareConnection() throws ClassNotFoundException, SQLException {
        String dcn = "oracle.jdbc.driver.OracleDriver";
        String url = "jdbc:oracle:thin:@JamesPJ-PC:1521:skypark";
        String usname = "system";
        String pass = "tiger";
        Class.forName(dcn);
        return DriverManager.getConnection(url, usname, pass);
    }

    public void doPost(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
        resp.setContentType("text/html");
        PrintWriter out = resp.getWriter();

        try {
            String phone1, dofb, date1, month, year, uname, fname, lname, address, city, state, country;
            String pin, email, password, gender, lang, qual, relegion, privacy, hobbies, fav;

            uname = req.getParameter("uname");
            fname = req.getParameter("fname");
            lname = req.getParameter("lname");
            date1 = req.getParameter("date");
            month = req.getParameter("month");
            year = req.getParameter("year");
            address = req.getParameter("address");
            city = req.getParameter("city");
            state = req.getParameter("state");
            country = req.getParameter("country");
            pin = req.getParameter("pin");
            email = req.getParameter("email");
            password = req.getParameter("password");
            gender = req.getParameter("gender");
            phone1 = req.getParameter("phone");

            lang = "";