this is just some code that i thourght of of the top of my head hope it helps.
Imports Microsoft.Office.Interop
Imports System.Runtime.InteropServices
Public Class Form_Main
Public MyExcel As New Excel.Application
public VarYourString1 as string = "your value"
sub Write_Data()
MyExcel.Visible = True
MyExcel.Sheets(Sheet1).Select()
MyExcel.Range("A1048575").End(Excel.XlDirection.xlUp).Select()
MyExcel.ActiveCell.Offset(1, 0).Select()
MyExcel.ActiveCell.Offset(0, 2).Select() move right 2 cells
MyExcel.ActiveCell.Offset(0, -1).Select() move left 1 cell
MyExcel.ActiveCell.Offset("A1").Select()
MyExcel.ActiveCell.Value = VarYourString1
MyExcel.ActiveCell.Offset(1, 0).Select()
MyExcel.Workbooks.Close()
End Sub
End Class