With that version the script automatically uses the first sheet in the spreadsheet.
If you want to name the sheet then you need to change every instance of:
var sh = ss.getSheets()[0];
to
var sh = ss.getSheetByName(e.parameter.SH);
remembering to republish your web app to a new version
and send a parameter &SH=Sheetname from your app (Sheetname being what ever the name of your sheet is, e.g. Sheet1)
Alternatively, you may want to look at:
or