need to change a macro that works only for a specific worksheet to work for others, also

I need to change a macro that works only for a specific worksheet to work for each among other worksheets individually [not sequentially], e.g.. to run in a worksheet with a different name like a modified copy of the original worksheet.
I'm working in Excel 2011. The following code runs in a worksheet called NOW. What's the easiest way to get it to run in all worksheets? I've looked around & tried various things but nothing has worked yet. I'm a super-newbie. Note: the comments are not specifically accurate because I edited the copied code to make it work for me but not the comments in case I needed to backtrack. [I got the original code here & it was a lifesaver]. Thanks!!! Shawn

Sub HistoricalData()
Dim TargetSht As Worksheet, SourceSht As Worksheet, SourceCol As Integer, SourceCells As Range


'If an error occurs skip code to the Err-Hanlder line and the display the error message.
On Error GoTo Err_Handler


'This is the sheet where your copy information from. Change "Sheet1" to the name of your soure sheet
Set SourceSht = ThisWorkbook.Sheets("NOW")


'Name of the sheet where data is to be copied to. Rename Sheet2 to the name of your target sheet
Set TargetSht = ThisWorkbook.Sheets("NOW")


'This is the cells you will copy data from. This is targeting cells B1 to the last used cell in column B
Set SourceCells = SourceSht.Range("e20:e30")


'This is finding the next column available in the target sheet. It assumes dates will be in row 1 and data in row 2 down
If TargetSht.Range("A1").Value = "" Then
'Cell A1 is blank so the column to put data in will be column #1 (ie A)
SourceCol = 1
ElseIf TargetSht.Range("IV1").Value <> "" Then
'Cell IV1 has something in it so we have reached the maximum number of columns we can use in this sheet.
'Dont paste the data but advise the user.
MsgBox "There are no more columns available in the sheet " & TargetSht.Name, vbCritical, "No More Data Can Be Copied"
'stop the macro at this point
Exit Sub
Else
'cell A1 does have data and we havent reached the last column yet so find the next available column
SourceCol = TargetSht.Range("IV1").End(xlToLeft).Column + 1
End If


'Put in the date in the appropriate column in row 1 of the target sheet
TargetSht.Cells(1, SourceCol).Value = Format(Date, "mm/dd/YYYY")


'We can now start copying data. This will copy the cells in column B from the source sheet to row 2+ in the target sheet
SourceCells.Copy TargetSht.Cells(4, SourceCol)


'Advise the user that the process was successful
MsgBox "Data copied successfully!", vbInformation, "Process Complete"


Exit Sub 'This is to stop the procedure so we dont display the error message every time.
Err_Handler:
MsgBox "The following error occured:" & vbLf & "Error #: " & Err.Number & vbLf & "Description: " & Err.Description, _
vbCritical, "An Error Has Occured", Err.HelpFile, Err.HelpContext




End Sub