To choose which modules you wish to use, select the Settings page in the sidebar, then select the Modules tab.

Module Settings Screen

Click on the Choose Modules button to open the module selection screen.

Module Selection Screen

Click on the modules you wish to use - a green tick will appear to indicate the module is selected.

To disable a module, click it again and the green tick will disappear.

Once you have chosen the modules you wish to use, click Confirm Selection.

All done! The modules page will now list your enabled modules:

Enabled Modules Screen