Problem in file OiMundoServlet.java - #algaworks

I'm following the E-book "Java EE7 with JSF, PrimeFaces and CDI". I created the Maven project, I edited the file pom.xml as the handbook guides, when I created the OiMundoServlet.java sample file, I noticed that errors appeared in the handbook, but when editing the file pom.xml again to eliminate the errors, those same mistakes are not gone. How to fix this?

• Note 1: I am using the latest version of Eclipse Java EE (Mars.1 Release (4.5.1))
• Note 2: When I added the apache 8 server, when linking the Maven project, I noticed the following error: Project facet Java version 1.8 is not supported .
• Note 3: The web.xml file was not created automatically. I had to create it because it reported an error in the file pom.xml in the line referring to <packaging>war</packaging> .

Follow the code:

package br.com.farmsystem.servlet;//essa linha apresenta erro

import java.io.IOException;//essa linha apresenta erro
import javax.servlet.ServletException;
import javax.servlet.annotation.WebServlet;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;

/**
* Servlet implementation class OiMundoServlet
 */
@WebServlet("/oi-mundo")
public class OiMundoServlet extends HttpServlet { //essa linha apresenta erro

    private static final long serialVersionUID = 1L;

    /**
     * @see HttpServlet#HttpServlet()
     */
    public OiMundoServlet() {
        super();//essa linha apresenta erro
        // TODO Auto-generated constructor stub
    }

    /**
     * @see HttpServlet#doGet(HttpServletRequest request, HttpServletResponse response)
     */
    protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {//essa linha apresenta erro
        // TODO Auto-generated method stub
    }

    /**
     * @see HttpServlet#doPost(HttpServletRequest request, HttpServletResponse response)
     */
    protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {//essa linha apresenta erro
        // TODO Auto-generated method stub
    }

}