You can use the Columns collection:
using (SqlConnection con = new SqlConnection(strConnect))
{
DataTable dt = new DataTable();
using (SqlDataAdapter da = new SqlDataAdapter("SELECT TOP 20 Title FROM Videos ORDER BY Title ASC", con))
{
da.Fill(dt);
}
DataColumn dc = dt.Columns[0];
}
But that won't give you access to the actual values in each column of the table.
For that, you need to iterate the Rows collection:
foreach (DataRow row in dt.Rows)
{
Console.WriteLine(row[0]);
}