string constringx = "Provider=Microsoft.Jet.OLEDB.4.0;Data Source="+ _
  Speicherort +";Extended Properties=Excel 8.0";
string sqly = "CREATE TABLE [Tabelle2$] (A1 char(100), a2 char(100))";
string sqlx = "INSERT INTO[Tabelle2$] (A1) VALUES ('Test123')";
OleDbConnection conx = new OleDbConnection(constringx);
OleDbCommand cmdx = new OleDbCommand(sqly, conx);
try
{
  cmdx.Connection.Open();
  cmdx.ExecuteNonQuery();
  cmdx.CommandText = sqlx;
  cmdx.ExecuteNonQuery();
}
catch (OleDbException exc)
{
  //Fehlermeldung
}
finally 
{
  cmdx.Connection.Close();
}