The Circuit Playground is screwed onto the Crickit using the included standoffs and screws. See this guide for assembly and more about Crickit.
The two servos plug into servo ports 1 and 2. The black wire faces the round Circuit Playground Express, the lightest color wire faces out.
If you want to add an on/off switch, solder it inline with the power wire going to the battery case. Plug the battery holder into the Crickit's power port.