I assume you are looking for something like this:
private void checkBox1_CheckedChanged(object sender, EventArgs e) {
if (checkBox1.Checked)
checkBox1.ForeColor = Color.Green;
else
checkBox1.ForeColor = Color.Red;
}
, Checked CheckBox . , checkBox1.Checked , Checked == true !checkBox1.Checked ( else) , Checked == false