GST is charged on the full fare passengers pay you for ride-sourcing services. The full fare, which includes GST, is generally calculated by the platform you're using.
As a ride-sourcing driver, you need to report and pay the GST your business has collected using a business activity statement (BAS).
Once you have registered for GST, you can also use a BAS to claim a credit for any GST included in the price of any goods and services you buy for your business.
You need to report your GST payments monthly or quarterly on a BAS (you can't choose to report annually).