c# beginer

sorry for my bad english

hi a have start to use c# and il try to experimen with this language

in this part of code i have a label scrolling text and its works but i wand to reverce the scrolling? or to choose left to right or right to left but i cand find how :(, please can someone help me?

System.Text.StringBuilder sb = new System.Text.StringBuilder("hello world");

private void timer1_Tick(object sender, EventArgs e)

{

char ch = sb[sb.Length - 1];

sb.Remove(sb.Length - 1, 1);

sb.Insert(0, ch);

label3.Text = sb.ToString();

label3.Refresh();

}