If you want to see how much you have earned since your registration, just go to your Dashboard and scroll down to the Revenue box.
In the Dashboard, you will also find revenue statistics of Units in the last seven days.
To view your earnings during a specific period of time:
Click Report in the menu and choose the available areas (Sites, Units or other depending on your activity)
Select the date(s) of the time frame requested (for example, the last month) from the dropdown menu in the upper right
The earnings generated will be per line in the "Revenue" column.