You can lay down the Powerboost 1000C and PAM8302 amplifier on the enclosure to get an idea for how long the power and ground wires need to be. Cut two pieces of 26AWG silicone-coated stranded wires.
Connect the audio cable to the amp by heating A+ and A- pins with the tip of the soldering iron. Insert the white channel wire to A+ and the ground wire to A-.
Connect Speaker to Amp
Apply solder to the positive and negative pins on the amplifier and insert the + and - wires from the speaker to the amp.