How to save and close an excel file?

I'm building a macro to get next free number from an excel file.

Everything seems to work fine, but it looks like the file is left "open" after running this code (file is "locked" if I try to open it).

I feel that I should save and close this file, but how to do it?

Best regards,

TapaniS

------------------ code -------

Sub ReadfromExcel()

Set excelapp = New Excel.Application
excelapp.Visible = False

Dim Findex As Integer
Dim Frange As String
Findex = 2
Frange = "A" + CStr(Findex)


FileName = "C:\Solid\File.xls"
Set Workbook = excelapp.Workbooks.Open(FileName)

Do Until (excelapp.Range(Frange) <> "X")
  Findex = Findex + 1
  Frange = "A" + CStr(Findex)
Loop

excelapp.Range(Frange).Select
excelapp.ActiveCell.FormulaR1C1 = "X"

Frange = "B" + CStr(Findex)
DwgNo.Text = excelapp.Range(Frange)

End Sub

SolidworksApi macros