public Form2(List <Uczestnik> ls, int ind, Action action)
{
InitializeComponent();
this.ls = ls;
this.ind = ind;
this.uc = ls[ind];
this.tsk = new Task(action);
showRecord();
}
private void button1_Click(object sender, EventArgs e)
{
ls[ind] = new Uczestnik(textBox1.Text, textBox2.Text, textBox3.Text, numericUpDown1.Value);
tsk.RunSynchronously();
this.Close();
}