Hello everyone.

I wrote ftp, created a form, made buttons, assigned functions by buttons. At first there was no main, added main, now I don’t know how to call the form from the main.

using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Data;
using System.Drawing;
using System.Linq;
using System.Text;
using System.Windows.Forms;
using FTP_lib;
namespace Project1 {
    static void Main() {
    }
    public partial class Form1: Form {
        ftp_Manager newFtpManager = new ftp_Manager();
        public Form1() {
            InitializeComponent();
        }
        private void username_txtb_TextChanged(object sender, EventArgs e) {
        }
        private void Form1_Load_1(object sender, EventArgs e) {
            newFtpManager.ftp_Username = username_txtb.Text;
            newFtpManager.ftp_Password = password_txtb.Text;
        }
        private void getContent_Click(object sender, EventArgs e) {
            newFtpManager.getContent("ftp://youdomain.com");
        }
        private void upload_file_Click(object sender, EventArgs e) {
            newFtpManager.UploadFile("ftp://yourdomain.com/filedestination", "C:\\myfile.exe");
        }
        private void donwload_button_Click(object sender, EventArgs e) {
            newFtpManager.DownloadFile("ftp://ftp.mama.tomsk.ru/festival/", "C:\\Download");
        }
        private void delete_file_Click(object sender, EventArgs e) {
            newFtpManager.DeleteFile("ftp://yourdomain.com/file.exe");
        }
    }
}
Answer 1, authority 100%
Create an instance of this form.
Form1 example = new Form1();
example.Show();

Added from comment. 
Main try to change as little as possible. When you need to call the desired form, use the AddWindow method: 
public partial class Form1: Form

{

  public Form1 ()

  {

    InitializeComponent ();

  }

  public void AddWindow ()

  {

    Form2 examp = new Form2 ();

    examp.Show ();

  }

}


Answer 2, authority 50% 
static void Main () is not needed in forms. 
and in the file (by default) program.cs there should be lines 
static void Main () 
{

    Application.EnableVisualStyles ();

    Application.SetCompatibleTextRenderingDefault (false);

    Application.Run (new & lt; Name of your form & gt; ());

  }