I'm having a hard time in grouping my data via ReportViewer. My friend told me to use List in grouping but I don't have a clue on how to do it so I'm requesting help from you guys if you can teach me. Thanks

The report wizard will group the data for you, just set the datasource of the report as a list.

Here is an example of report creation.

As for setting the report source, name it dataset one and use the following code to set the source. (Be sure to have the correct property names in your list of objects.)

Dim ReportPath as String = "MyAssemblyName.EmbededReportName"
rvwReports.LocalReport.ReportEmbeddedResource = ReportPath
rvwReports.LocalReport.DataSources.Add(New Microsoft.Reporting.WinForms.ReportDataSource("DataSet1", lstMySource))
Me.rvwReports.RefreshReport()