how to update list items in share point , using Windows Form Application

You have to sharepoint model (prior to 2010 vesion) / client object model (2010) to create the list into sharepoint list.

string connString = "Provider=Microsoft.Jet.OLEDB.4.0;Data Source=" + FileName + ";Extended Properties=Excel 8.0;"; OleDbConnection oledbConn = new OleDbConnection(connString);
oledbConn.Open();
OleDbCommand cmd = new OleDbCommand("SELECT * FROM [Sheet1$]", oledbConn);
OleDbDataAdapter oleda = new OleDbDataAdapter();
oleda.SelectCommand = cmd;
DataSet ds = new DataSet();
oleda.Fill(ds, "exceldata");  

using(SPSite site = new SPSite("sharepoint site url"))
{  using (SPWeb web = site.OpenWeb())
{
 foreach (DataRow row in ds.Tables[0].Rows)
 {  
 SPList list = web.Lists["YourList"];  
SPListItem Item = list.Items.Add();  
item["Title"] = row.ItemArray[0].ToString();  
item["Description"] = row.ItemArray[1].ToString()  item.Update();
 } } }

http://spreadsheet2splist.codeplex.com/

Hope this helps you.