how to create a notepad in windows form c#.net

Question

Dear All

I have almost crated a notepad for using windows form and c#.net . In this application i have used a richTextBox and menustrip control, all coding i have done but word warp code not work, i have using this code but this code show an error "instance ref not set"

wordWrapToolStripMenuItem.Checked = !(wordWrapToolStripMenuItem.Checked);
richTextBox1.WordWrap = wordWrapToolStripMenuItem.Checked; 

Kindly please help me and advice the code of wordwrap

also advise me the code of find, find next, replace and goto.