How do I save a WorkBook using only select cells macro

Give this a try...

Option Explicit

Sub SaveInvWithNewName()
    Dim NewInv As Variant
    Dim NewBook As Workbook
    NewInv = "C:\Invoices\LeeValley-Inv" & "-" & ActiveSheet.Range("F2").Value & ".xlsx"
    ActiveSheet.Range("A1:K40").Copy
    Set NewBook = Workbooks.Add
    NewBook.Worksheets("Sheet1").Range("A1").PasteSpecial (xlPasteValues)
    NewBook.SaveAs Filename:=NewInv
    MsgBox "File Saved to C:\Invoices"
End Sub