While the innards of most toys these days have more than just a wire, if you can trace the "activate" button back to the circuit board- those two are the wires to jump
There are two great examples of soldering and switching specific toys below:
(Hopefully I'll give you an adapting/soldering lesson soon!)
https://www.instructables.com/id/Holiday-Toy-Switch-Adapting/ (Awesome walk-throughs of adapting)
Don't be afraid- Practice on a toy from a garage sale on your first one- you'll do great!