Hi Gruden,
If you have 3 pictures in the picture box and you gonna validate each and every picture box then
PictureBox1 = Image1;
PictureBox2 = Image2;
PictureBox3 = Image3;
At page load, show first picture that is
PictureBox1.Visible = True;
PictureBox2.Visible = False;
PictureBox3.Visible = False;
At button click when user answers correct then
PictureBox1.Visible = False;
PictureBox2.Visible = True;
PictureBox3.Visible = False;
Similarly for 3rd picture box.
PictureBox1.Visible = False;
PictureBox2.Visible = False;
PictureBox3.Visible = True;
If user enters wrongly then
PictureBox1.Visible = False;
PictureBox2.Visible = False;
PictureBox3.Visible = False;
MessageBox.Show("Wrong answer");
Hope this helps you a bit.
Regards,
RK