If this is a question of VB, not VB.NET, the code below shows how to create instance of MS Excel application and how to write and read data.
Option Explicit
Sub ReadWriteExcel()
Dim oExc As Object, oWbk As Object, oWsh As Object
On Error GoTo Err_ReadWriteExcel
Set oExc = CreateObject("Excel.Application")
Set oWbk = oExc.Workbooks.Add()
Set oWsh = oWbk.Worksheets(1)
oWsh.Range("A1") = Environ("username")
MsgBox "Welcome " & oWsh.Range("A1") & "!", vbInformation, "Information..."
Exit_ReadWriteExcel:
On Error Resume Next
If Not oExc Is Nothing Then oExc.Visible = True
Set oWsh = Nothing
Set oWbk = Nothing
Set oExc = Nothing
Exit Sub
Err_ReadWriteExcel:
MsgBox Err.Description, vbExclamation, Err.Number
Resume Err_ReadWriteExcel
End Sub