in a webpart after the button is clicked the textbox and label should be displayed

protected void Button1_Click(Object sender,Eventargs e)
{
     label1.visible = true; // set property as visible false prior
     textbox1.visible = true; //set property as visible false prior
}

protected void Button1_Click(Object sender,Eventargs e)
{
    Label lable1 = new Label();
    TextBox textbox1 = new TextBox();
    
    //you will need to have a container( placeholder or panel) control where you want to add them
   contarinerControl.Add(label1);
   contarinerControl.Add(textbox1);

 
}