A  B  C  D
    -  -  -  -
1 | 2  5  9  12
2 | 5  8  4  5
3 | 3  1  2  6

ThisWorkbook.Sheets("name of sheet 2").Range("A1")

ThisWorkbook.Sheets("name of sheet 2").Activate

=SUM([Name-Of-Sheet2]!A1:D1)

ActiveWorkbook.worksheets("Sheet2").cells(aRow,aCol).Value=someval

someVal=ActiveWorkbook.worksheets("Sheet2").cells(aRow,aCol).Value

Sub TEST()
Dim value1 As String
Dim value2 As String
value1 = ThisWorkbook.Sheets(1).Range("A1").Value 'value from sheet1
value2 = ThisWorkbook.Sheets(2).Range("A1").Value 'value from sheet2
If value1 = value2 Then ThisWorkbook.Sheets(2).Range("L1").Value = value1 'or 2
End Sub

objWorkbook.WorkSheets(1).Activate
objWorkbook.WorkSheets(2).Activate

SomeVal=ActiveWorkbook.worksheets("Sheet2").cells(aRow,aCol).Value

SomeVal = ThisWorkbook.Sheets(2).cells(aRow,aCol).Value