Try using like this:
using System.Data;
using System.Data.OleDb;
...
OleDbConnection con = new OleDbConnection(@"Provider=Microsoft.Jet.OLEDB.4.0;Data Source=C:\Book1.xls;Extended Properties=Excel 8.0");
OleDbDataAdapter da = new OleDbDataAdapter("select [ExcelColumName], [ExcelColumName] from MyObject", con);
DataTable dt = new DataTable();
da.Fill(dt);
Replace "ExcelColumName" with excel column name. And remember, square braces will be there.