This article shows how to convert text into PDF format and a database table take form and ContextMenuStrip in that Save to PDF and Save to DB and 
also take RichtxtBox and write coding click event.

private void saveToPDFToolStripMenuItem_Click(object sender, EventArgs e)
{
SaveFileDialog s = new SaveFileDialog();
s.InitialDirectory = "C:";
s.Filter = "Pdf file(*.pdf)|*.pdf";

if (s.ShowDialog() == DialogResult.OK)
{
Document Doc = new Document();
PdfWriter.GetInstance(Doc, new FileStream(s.FileName, FileMode.Create));
Doc.Open();
Doc.Add(new Paragraph(richTextBox1.Text));
Doc.Close();
}
}

private void saveToDBToolStripMenuItem_Click(object sender, EventArgs e)
{
{
SqlConnection cn = new SqlConnection("Data Source=.;Initial Catalog=master;User ID=sa;word=coign");
string s1 = "Insert into Dat values('" + richTextBox1.Text + "')";
SqlCommand cmd = new SqlCommand(s1, cn);
cn.Open();
cmd.ExecuteNonQuery();
cn.Close();

MessageBox.Show("save in DB");
}
}