Plug your speaker into the mini jack port at the top of the Monster M4sk (next to the USB port).
Plug your battery in to the 2-pin JST port on the right side.
Plug your servo into the 3-pin JST port below the battery port.
Finally, plug the JST connector with the male headers into port D2 on the left side of the Monster M4sk. Cut off the red (middle) wire -- this wire is not needed and can short out and damage your Monster M4sk if it contacts the other wires.
The remaining black and white wires will connect to the legs on your trigger button.
You can leave the trigger button in the breadboard, or you can solder the wires from the connector directly onto the legs for a slicker implementation. It might be fun to place the button under Fizzgig's nose so he barks when you boop him on the nose. For my wearable installation, I extended the button's wires and hid it under my fur stole so I can trigger it with my thumb.
It would also be fun to hook up a large arcade button or the like, for maximum interactive fun.
Testing / Troubleshooting
Once you have all the components hooked up, power the board on and press the button. You should hear a barking sound and the servo will move. If this happens, hooray! You're ready to install everything into your puppet.
If the board doesn't power up when you plug it in, make sure the on/off switch is in the "on" position. It's tiny and easy to miss!
If the servo moves continuously, you may have your button hooked up incorrectly. Be sure you're connected to two separate legs, and not connected "across" the button accidentally.
If the eyes look yellow and Fizzgig-like, but the button / servo doesn't seem to work at all, check to be sure you've got FIZZGIG.UF2 correctly installed on the board. Check the Software page and make sure you've followed all the steps.