How do I pass data from another page?

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C#

DevExpress

I have two forms. one is Main Entry Form and other is District. In District form I Add district and i want that the District i add in District Table Show in District Combo Box of Main Entry Form.

What I have tried:

private void Mian_Entry_Form_Load(object sender, EventArgs e)
{

// TODO: THIS CODE LOAD DISTRICT TO COMBOBOX IN MAINENTRY FORM

string q = string.Format("Select districtid, districtname from district");
DataTable dt = new DataTable();
SqlDataAdapter sd = new SqlDataAdapter(q, connection);
sd.Fill(dt);
foreach (DataRow dr in dt.Rows)
{
comboBoxEditdistrict.Items.Add(dr[1].ToString());
//comboBoxEditdistrict.
}