Dim wrkRng As Range
Dim hChoice As Integer
Dim choice As String
Dim debugVar As Variant
Dim qtt As Integer

Sub Highlight() 'Q1
    On Error GoTo ErrHandler:
'Part A
    ThisWorkbook.ActiveSheet.Cells.FormatConditions.Delete
'Part B
    Set wrkRng = Range(Range("FirstP"), Range("FirstP").End(xlDown).End(xlToRight))
'Part C
    hChoice = InputBox("Choose 1 to highlight a product name" & vbNewLine & "Choose 2 to highlight a quantity order value")
'Part D
    If hChoice = 1 Then
'Part E
        choice = InputBox("Which product would you like to highlight ?")
        debugVar = wrkRng.Columns(1).Find(choice, , , xlWhole)
        wrkRng.FormatConditions.Add Type:=xlExpression, Formula1:="=$B31=" & Chr(34) & choice & Chr(34) ' Changer le $B31 par la valeur relative du nom FirsProduct
        wrkRng.FormatConditions(1).Interior.Color = vbYellow
'Part D
    ElseIf hChoice = 2 Then
        choice = InputBox("enter an inequality sign for the quantity highlight rule (<, >, <=, or >=)")
            If Application.WorksheetFunction.Or(choice = "<", choice = ">", choice = "<=", choice = ">=") Then
                qtt = InputBox("Enter a numeric value for the quantity highlight rule")
'Part E
                If Application.WorksheetFunction.Or(choice = "<", choice = "<=") Then
                    If Application.WorksheetFunction.Min(wrkRng.Columns(2)) > qtt Then
                        MsgBox ("The quantity you use for the highlight rule is strictly lower than the minimum of the quantity")
                        Exit Sub
                    End If
                Else
                    If Application.WorksheetFunction.Max(wrkRng.Columns(2)) < qtt Then
                        MsgBox ("The quantity you use for the highlight rule is strictly greater than the maximum of the quantity")
                        Exit Sub
                    End If
                End If
                'We are supposed to be here only if there is no greater value max and lower value than min depending of user input
'Part F
                wrkRng.FormatConditions.Add Type:=xlExpression, Formula1:="=$C31" & choice & qtt   ' Changer le $C31 par la valeur relative du nom FirsProduct"
                wrkRng.FormatConditions(1).Interior.Color = vbYellow
            Else
                Exit Sub
            End If
    Else
        MsgBox ("Your choice need to be between 1 and 2")
    End If

    Exit Sub

ErrHandler:
    MsgBox ("Enter a valid product name")
    Exit Sub
End Sub