Combine files in VBA

I read some threads, and write down this code. The purpose is for combining excel files into one.
For example, I have 10 data files. All of them are in the same format with 2 sheets. I want to use the VBA code to combine them into one excel file.
After testing, lots of data are missing. I use F8 to check it step by step, and found out that the new files data will replace the old one, etc.

What should this code be amended for my purpose?

If FileNum > 0 Then
        Dim Arr
        ReDim Arr(1 To FileNum, 1 To 2)
        For FileNum = LBound(MyFiles) To UBound(MyFiles)
            Set mybook = Workbooks.Open(FilePath & MyFiles(FileNum))
            Sheets("CLASS A").Activate
            RowCount = Range("A1").End(xlDown).Row
            Arr(FileNum, 1) = Range(Range("A2"), Range("E2").Offset(RowCount - 1))
        
            Sheets("CLASS B").Activate
            RowCount = Range("A1").End(xlDown).Row
            Arr(FileNum, 2) = Range(Range("A2"), Range("E2").Offset(RowCount - 1))
        
            ActiveWorkbook.Close
            Sheets("CLASS A").Activate
            Range("A2").Resize(UBound(Arr(FileNum, 1), 1), UBound(Arr(FileNum, 1), 2)) = Arr(FileNum, 1)
            Sheets("CLASS B").Activate
            Range("A2").Resize(UBound(Arr(FileNum, 2), 1), UBound(Arr(FileNum, 2), 2)) = Arr(FileNum, 2)
        
        Next FileNum
                    
    End If

Thank you!!