You may add one or more symbols (using a comma-separated or space-separated string) with the symbol entry form at the top of the Watchlist page. Additionally, you may add a symbol to any Watchlist from the symbol's quote page.
An example of adding multiple symbols at once:
IBM MSFT AMZN APPL
Hint: If you have a list of symbols in an excel spreadsheet, just copy the column containing the symbols and paste into the "Enter Symbol" box on the Watchlist page.
New additions to the Watchlist are automatically added to the bottom of the table. You may change the sort order of the Watchlist entries using the "Edit Watchlist" page.