Excel VBA - Find and Replace from External File - vba

Question

I have a file that I would like to run a Find and Replace on using data from another Excel file.
I have this so far, what am I doing wrong?
Sub LegalName()
Dim NameListWB As Workbook
Dim NameListWS As Worksheet
Set NameListWB = Workbooks.Open("File.xlsx")
Set NameListWS = NameListWB.Worksheets("Sheet1")
Dim rng As Range
Set rng = NameListWS.Range("A:B").Select
Do Until IsEmpty(ActiveCell)
Worksheets("Sheet1").Columns("F").Replace _
What:=ActiveCell.Value, Replacement:=ActiveCell.Offset(0, 1).Value, _
SearchOrder:=xlByColumns, MatchCase:=False
ActiveCell.Offset(1, 0).Select
Loop
End Sub

Answer 1

I see that you started by declaring your objects but missed out on few. Also, you need to avoid the use of .Select Interesting Read
Is this what you are trying (UNTESTED)?
Sub Sample()
Dim NameListWB As Workbook, thisWb As Workbook
Dim NameListWS As Worksheet, thisWs As Worksheet
Dim i As Long, lRow As Long
'~~> This is the workbook from where your code is running
Set thisWb = ThisWorkbook
'~~> Change this to the sheet name where you want to replace
'~~> in Column F
Set thisWs = thisWb.Sheets("Sheet1")
'~~> File.xlsx
Set NameListWB = Workbooks.Open("C:\File.xlsx")
Set NameListWS = NameListWB.Worksheets("Sheet1")
With NameListWS
'~~> Find last row in Col A of File.xlsx
lRow = .Range("A" & .Rows.Count).End(xlUp).Row
'~~> Loop though Col A
For i = 1 To lRow
'~~> Do the replace
thisWs.Columns(6).Replace What:=.Range("A" & i).Value, _
Replacement:=.Range("B" & i).Value, _
SearchOrder:=xlByColumns, _
MatchCase:=False
Next i
End With
End Sub