Form f = new Form();
                Button btn = new Button();
                btn.Click += (o, j) => { f.Close(); };//点击关闭
                f.Controls.Add(btn);
                f.Show();

------解决方案--------------------
是创建一个新的窗体咋。
在Form1的button1_Click事件中定义调出窗体就行了。具体如下：
   private void button1_Click(object sender, EventArgs e)
       {
           try
           {
               Form form2 = new Form();
               InitForm(form2);

               form2.ShowDialog();
           }
           catch (Exception ex)
           {
               System.Diagnostics.Debug.WriteLine(ex.Message);
           }
       }

       private void InitForm(Form form2)
       {
           Button button2 = new System.Windows.Forms.Button();
           button2.Location = new System.Drawing.Point(99, 111);
           button2.Name = "button2";
           button2.Size = new System.Drawing.Size(91, 33);
           button2.TabIndex = 0;
           button2.Text = "button2";
           button2.UseVisualStyleBackColor = true;

           form2.AutoScaleDimensions = new System.Drawing.SizeF(6F, 12F);
           form2.AutoScaleMode = System.Windows.Forms.AutoScaleMode.Font;
           form2.CancelButton = button2;
           form2.ClientSize = new System.Drawing.Size(292, 273);
           form2.Controls.Add(button2);
           form2.Name = "Form2";
           form2.Text = "Form2";
           form2.ResumeLayout(false);
       }

窗体的CancelButton 这个属性就是点击canelButton，可以关闭该窗体

------解决方案--------------------
Form1
button1.Click +=(o,e) => {Form2 f =  new Form2();f.Show();}
Form2
button1.Click +=(o,e) => {this.Close();}