dudas c#

[Peterpay]

private void Form3_Load(object sender, EventArgs e)
{
richTextBox1.KeyPress += new KeyPressEventHandler(richTextBox1_KeyPress);


}

void richTextBox1_KeyPress(object sender, KeyPressEventArgs e)
{
if (char.IsLetter(e.KeyChar))
{
e.KeyChar = char.ToUpper(e.KeyChar);
}
}

con esto puedes solucionarlo