To reference range of cells you can use Range(Cell1,Cell2), sample:
Sub RangeTest()
Dim testRange As Range
Dim targetWorksheet As Worksheet
Set targetWorksheet = Worksheets("MySheetName")
With targetWorksheet
.Cells(5, 10).Select 'selects cell J5 on targetWorksheet
Set testRange = .Range(.Cells(5, 5), .Cells(10, 10))
End With
testRange.Select 'selects range of cells E5:J10 on targetWorksheet
End Sub