How do I know if the driver is successfully installed?

When the driver is completely installed.

Windows OS:

1. You should find a file named "Tablet setting" from the start menu. 
2. Enter into tablet setting and try to draw in the test area:
3. If you could get pressure sensitivity in the test area, the driver was installed well.

Mac:

1. You should find a "tablet" icon appeared in the task bar, click "Quick Setup" to enter into tablet setting.                                                                                  
2. Try to draw in the test area:                                                              
3. If you could get pressure sensitivity in the test area, the driver was installed well.