To add or sell shares in a Basket:
Adding shares: From the "Baskets" section, select the Basket you want to operate on. Tap on the "Add" option. You can acquire from 1 up to as many shares as needed to reach the maximum of 20,000.
Selling shares: Similarly, in the Basket section, select the option to sell. You can sell from 1 up to as many shares as needed to reach the maximum of 20,000.