creating a loop in a macro

Hi I'm new to this

I have an output file form database which is seperated into 26 differnt tabs relating to different parts of data base.

From this output file I have created different workbooks analysisng certain sheets from the output file seperataly( there is alot of analysis involed in the sheets)

changes are being to the data on a weekly bases so i have to copy & paste the data from the output file into the workbbooks were i analysise the data

I have created a macro
I have a generic coverhsheet in each of the workbooks were i do the analysis. One of the cells has a drop down menu givng me the option to select which i sheet i want update, The macros reads this cell and looks for this sheetname file in the latest output file (the file name is specified on the coversheet), then copies the updated data into the workbook were the analysis is done
This the code i have created
I want put a named range on the cover sheet with sheetnames that are being used from the output file, I want the macro to loop and update data in them specified file names.

I havent created a loop before and I'm finding it hard to understand how to start

Private Sub Newsub()
Range("H1").Select

ActiveCell.FormulaR1C1 = "=CELL(""filename"")"
Range("H1").Select
Calculate
Dim FilePath As String
Dim iCell As String

Worksheets("Cover_Page").Select
FilePath = ActiveSheet.Range("f1").Value
iCell1 = ActiveSheet.Range("f2").Value
iCell2 = ActiveSheet.Range("f3").Value
iCell3 = ActiveSheet.Range("f4").Value
If Not IsEmpty(iCell) Then 'checks for empty value, if found exits, if not opens workbook
    Workbooks.Open Filename:=FilePath & iCell1 & ".xlsx", ReadOnly:=True
Else
    Exit Sub

End If



 'This copies the selected data
     Workbooks(iCell1).Activate
Workbooks(iCell1).Worksheets(iCell2).Select
    x3 = Application.WorksheetFunction.CountIf(Range("a:a"), ">0") + 1
    x4 = Application.WorksheetFunction.CountIf(Range("1:1"), "<>")

     Range(Cells(2, 1), Cells(x3, x4)).Select
    Selection.Copy
    Workbooks(iCell3).Activate
Workbooks(iCell3).Worksheets(iCell2).Select
    Range(Cells(2, 1).Address).Select
    Selection.PasteSpecial Paste:=xlPasteValues

  
Workbooks(iCell1).Close False

End Sub

Thanks