DataSet resembles database. DataTable resembles database table, and DataRow resembles a record in a table. If you want to add filtering or sorting options, you then do so with a DataView object, and convert it back to a separate DataTable object.

If you're using database to store your data, then you first load a database table to a DataSet object in memory. You can load multiple database tables to one DataSet, and select specific table to read from the DataSet through DataTable object. Subsequently, you read a specific row of data from your DataTable through DataRow. Following codes demonstrate the steps:

SqlCeDataAdapter da = new SqlCeDataAdapter();
DataSet ds = new DataSet();
DataTable dt = new DataTable();

da.SelectCommand = new SqlCommand(@"SELECT * FROM FooTable", connString);
da.Fill(ds, "FooTable");
dt = ds.Tables["FooTable"];

foreach (DataRow dr in dt.Rows)
{
    MessageBox.Show(dr["Column1"].ToString());
}

To read a specific cell in a row:

int rowNum // row number
string columnName = "DepartureTime";  // database table column name
dt.Rows[rowNum][columnName].ToString();

If ds is the DataSet, you can access the CustomerID column of the first row in the first table with something like:

DataRow dr = ds.Tables[0].Rows[0];
Console.WriteLine(dr["CustomerID"]);

If this is from a SQL Server datebase you could issue this kind of query...

Select Top 1 DepartureTime From TrainSchedule where DepartureTime > 
GetUTCDate()
Order By DepartureTime ASC

GetDate() could also be used, not sure how dates are being stored.

I am not sure how the data is being stored and/or read.