Here is a solution:
Sub FindPAY()
lastrow = Sheets("Sheet1").Range("A" & Rows.Count).End(xlUp).Row
For i = 2 To lastrow
Select Case Sheets("Sheet1").Cells(i, 6)
Case 1800
Row = 1
Case 1900
Row = 2
Case 2000
Row = 3
Case 2400
Row = 4
Case 2800
Row = 5
Case 4200
Row = 6
End Select
For j = 2 To 41
If Sheets("Sheet1").Cells(i, 7).Value > Sheets("Sheet2").Cells(j, Row) Then
rowfound = j
Exit For
End If
Next j
Sheets("Sheet1").Cells(i, 8) = Sheets("Sheet2").Cells(rowfound - 1, Row)
Next i
End Sub
There is no table for GRADE PAY 4000 in Sheet2. You have to add that and also add a case select for that.