To add a stock to your Watchlist, type the name of the company or the ticker symbol of the company in this search bar:
Select the stock from the dropdown menu, and then click the blue 'Add Stock' button.
You will then see the stock added to the bottom of your Watchlist on the left-hand side of the screen.
To indicate that you actually own the stock, click the stock icon on your Watchlist.
You will see the following:
Here, you can toggle between left and right. Clicking the button once will indicate that you own the stock.
Stocks that are marked as owned will be green in your Watchlist.
Stocks that are marked as watched will be blue in your Watchlist.