copy work sheet from another work book into already exits sheet

hi,
i want copy and paste worksheet from "user rasied" workbook to summary workbook. in that(summary) having user system generated sheet already exits with data i want to paste data from "user rasied" workbook to (summary) user system generated copy to below from last row used can u help me

Sub mmm()
Dim pasteSheet As Worksheet
Dim strFileToOpen As String
strFileToOpen = Application.GetOpenFilename _
(Title:="Please choose a file to open", _
FileFilter:="Excel Files *.xls* (*.xls*),")
Workbooks.Open Filename:=strFileToOpen


Set copySheet = Worksheets("sheet2")
Set pasteSheet = Worksheets("sheet1")
Range("A1").Select
Range(Selection, Selection.End(xlDown)).Select
Range(Selection, Selection.End(xlToRight)).Select
Selection.Copy
pasteSheet.Cells(Rows.Count, 1).End(xlUp).Offset(1, 0).PasteSpecial xlPasteValues
Application.CutCopyMode = False
Application.ScreenUpdating = True

End Sub
i have written the code but it was copying the within the sheet only. i want copy the sheet by opening the workbook and select the sheet