how to automatically highlight the whole row?

Right click on your sheet and select View-> Code. Enter this code in there -

Private Sub Worksheet_SelectionChange(ByVal Target As Range)
Rows(Target.Row & ":" & Target.Row).Select
End Sub

Now save your file and come back to the sheet. Whichever cell you click on, the row will be highlighted.

That code will highlight the whole row because it is selected. Not a good option if you actually want to work with the cell tht was originally selected

Option Explicit
Const iNoColour As Integer = Not (0)
Private Sub Worksheet_SelectionChange(ByVal Target As Range)
    Dim iColour As Integer
    ' Note: Don't use IF you have Conditional formating that you want to keep!
    On Error Resume Next
    iColour = Target.Interior.ColorIndex
    ' Leave On Error ON for Row offset errors
    If iColour < 0 Then
        iColour = 34
    Else: iColour = iColour + 1
    End If
    ' Need this test in case Font colour is the same
    If iColour = Target.Font.ColorIndex Then iColour = iColour + 1
    Cells.FormatConditions.Delete
    ' Horizontal colour highlight
    With Target
        .EntireRow.FormatConditions.Add Type:=2, Formula1:=iNoColour    'Or just 1 '"TRUE"
        .EntireRow.FormatConditions(1).Interior.ColorIndex = iColour
    End With
End Sub

Worksheet event code is stored on a worksheet module. To add it to your worksheet, do the following:

Copy the code
Select the worksheet in which you the code to run
Right click on the sheet tab and choose View Code, to open the Visual Basic Editor.
Where the cursor is flashing, choose Edit | Paste