Search xlsx for a value, if found replace with different value - vba

Question

So I'm either being too specific, or not searching well enough, because I can't find anything that answers my question. So I came here for help. Here is the situation:
I have an excel sheet, let's call it "CustomerCodeReference", that has a column (A) of Customer Codes (I.E. A2001, A2002, B3900, Q2838, etc, these are NOT necessarily in order) About 3000 of them, and in the next column over (B), I have the group that code represents (I.E. Accounts Primary, Accounts Secondary, Admin Group, User Group, just different names and etc.)
Now, from our company server I can export a spreadsheet of reports from customers, but the problem is, they are labelled by customer code, + a report serial number. The sheet exports as several columns, but one of the columns (G) contains the Customer code and serial number, and each row is a report, sometimes hundreds depending on the date range set. So keeping with the example, let's say it's a report from "Accounts Primary" It's labelled A2001234567 (where everything after the customer code of 'A2001' is the report serial number) sometimes, the report may be from several customers, so that column may have more than one code+SN in it per row.
Given that I have thousands of these codes and groups, is there some macro I can create that every time I export the spreadsheet of reports, I can maybe copy over the "CustomerCodeReference" sheet, and have it automatically search the column of customer codes and SNs, then either replace the code with the actual name, or place the actual name in another (empty) row further back. So I can basically easily reference whose report it is without having to look up the code each time?
I realize I will need to do this in VBA, as there is no formula I can think of that will work.
I have some pro's I think going for me:
-I already have the Master code list, so even though there are thousands of codes, they are all listed in Column A, and the actual name of group they reference is in column B.
-The codes are consistent, a letter, followed by 4 numbers, so always 5 characters long.
-When pulling the report, it always names the worksheet "Customer Reports" so it's easy to reference
These are constants. So I need the actual customer name to either replace the code (while leaving the serial number intact) or if easier, add the actual name to the next empty column on the same row. I also might need to share this with coworkers, so basically just send them the "CustomerCodeReference" sheet and when they add it to all their pulled spreadsheets, it does the same thing. (Macros will be enabled, so no worries there)
Is this too complicated an idea? or can I pull it off? Thanks in advance for the help!
EDIT: I apologize, I complete forgot to attach any sort of code. Here is what I have come up with in VBA, but not sure if I am on the right track as it does not complete the replacement, and I can't quite get it to add values in next available empty cell.
Sub replaceStringInCell()
'declaring my sheet I want to change change customer codes in
Dim CustomerCodes As Range
'declaring strings I will be replacing and with what I will be replacing them
Dim ReportNumbers As Range
Dim CustomerNames As Range
'identifying column I am working to replace, also trying to shoot for next empty column
Set CustomerCodes = PulledReports.Worksheets("Customer Reports").Range("G:G")
'specifying my strings
ReportNumbers = PulledReports.Worksheets("Customer Reports").Range("G:G")
myReplacementString = PulledReports.Worksheets("Customer Code Reference").Range("A:A")
'replace string in cell
CustomerCodes.Value = Replace(Expression:=CustomerCodes.Value, Find:=ReportNumbers, Replace:=CustomerNames)
End Sub

Answer 1

This should do the trick:
Sub stack_overflow()
Dim cust As Worksheet
Dim ref As Worksheet
Set cust = ActiveWorkbook.Worksheets("Customer Reports")
Set ref = ActiveWorkbook.Worksheets("Customer Code Reference")
'Finding next empty column
Dim column As Integer
column = cust.UsedRange.Columns.column + 1
'Filling this columns
For Each cell In cust.Range("G2:G" & cust.Cells(Rows.Count, "G").End(xlUp).Row)
cust.Cells(cell.Row, column).Value = Application.WorksheetFunction.VLookup(Left(cell.Value, 5), _
ref.Range("A2:B" & ref.Cells(Rows.Count, "B").End(xlUp).Row), 2, False)
Next cell
End Sub