I have a spreadsheet in Google docs which has daily stock for a small business. I have written a script which creates a copy of the script and then copies the closing stock
Darius, there is no way your Google App Script can navigate to other url. The most you can do is to present a hyperlink in a cell, so the user can click it: it will open in other tab, and of course, it needs user action to do so. (I don't want to bring the subject of HTML services, that's out of scope.)
These scripts run in Google servers. When a script opens a Doc or Spreadsheet, it do so to access its data, but not to show it on the browser.
Only "container bound scripts" (those you write from a document or spreadsheet) can mildly interact with the user interface, say adding menus or panels.
If you want to show some data, you can "range.setValues" it, or you can do a web page with a standalone script, using HTML Services, to show data obtained from spreadsheets.