Need help amending a find and mark macro.

Right, with the help of rondebruin, I have made a start. But still need help fine tunning it.
Need to change the search criteria? Need to search for more values, but cant seem to get it to work.
Also it searches for blank cells at the moment, how do I stop this? And it only searches one sheet? Cant seem to amend this for multiple sheets.
Someone Please help! My Vba is rubbish, but im really trying on this one
See code so far:

Sub Mark_cells_in_column()
Dim FirstAddress As String
Dim MyArr As Variant
Dim Rng As Range
Dim I As Long

With Application
.ScreenUpdating = False
.EnableEvents = False
End With

MyArr = Array(Range("A1").Value, Range("A2").Value)
With Sheets("Sheet2").Range("A:A")

.Offset(0, 1).ClearContents
For I = LBound(MyArr) To UBound(MyArr)

Set Rng = .Find(What:=MyArr(I), _
After:=.Cells(.Cells.Count), _
LookIn:=xlFormulas, _
LookAt:=xlWhole, _
SearchOrder:=xlByRows, _
SearchDirection:=xlNext, _
MatchCase:=False)

If Not Rng Is Nothing Then
FirstAddress = Rng.Address
   Do
Rng.Offset(0, 1).Value = Range("B1").Value
Rng.Offset(0, 2).Value = Range("C1").Value
Set Rng = .FindNext(Rng)
Loop While Not Rng Is Nothing And Rng.Address <> FirstAddress
End If
Next I
End With
With Application
.ScreenUpdating = True
.EnableEvents = True
End With
End Sub

This was posted in one of my previous posts, but no luck so far. If you look at my previous post you can see an explanation of what I need it to do. Thanks

PHP Code: 

Option Explicit
Sub Mark_Cells_In_Column()
 Dim FirstAddress As String, I As Long
 Dim MyArr As Variant, Rng As Range, Sh As Worksheet

 Sheets("Sheet1").Select
 With Application
    .ScreenUpdating = False
    .EnableEvents = False
 End With
 MyArr = Array(Range("A1").Value, Range("A2").Value)
 For Each Sh In ThisWorkbook.Worksheets
    If Sh.Name <> "Sheet1" Then
        With Sh.Range("A:A")
            .Offset(0, 1).ClearContents
            For I = LBound(MyArr) To UBound(MyArr)
                Set Rng = .Find(What:=MyArr(I), After:=.Cells(.Cells.Count), _
                    LookIn:=xlFormulas, LookAt:=xlWhole, SearchOrder:=xlByRows, _
                    SearchDirection:=xlNext, MatchCase:=False)
                If Not Rng Is Nothing Then
                    FirstAddress = Rng.Address
                    Do
                        Rng.Offset(0, 1).Value = Range("B1").Value  'B1<=|'
                        Rng.Offset(0, 2).Value = Range("C1").Value  'C1<=|'
                        Set Rng = .FindNext(Rng)
                    Loop While Not Rng Is Nothing And Rng.Address <> FirstAddress
                End If
            Next I
        End With
    End If
 Next Sh
 With Application
    .ScreenUpdating = True
    .EnableEvents = True
 End With
End Sub 


Hi, thanks, this seems to work great for multiple sheets. Is there a way to prevent it from searching if the cell is blank. Eventually I plan on having approximatelly 20 cells for search. eg MyArr=A1,A2,A3.........A20, so if cells A1 to A5 contain a value but A6 to A20 dont, then only want it to find the cells that are populated. At the moment if I have a value in A1 and nothing in A2 then it trys to add the values from B1 and C1 to the right of all the blank cells in column A on every worksheet (currently 250).
Thanks again.