The most basic ways to wire speakers are in serial or in parallel, or a combination of the two. Which to choose depends upon the amplifier and the speakers. In general, it is best to match the overall speaker load with the amplifier's output impedance to get maximum power transfer.
Wiring speakers in series, the impedance from each speaker adds to the rest. From the amplifier, the positive terminal connects to the positive terminal of the first speaker. The negative terminal of the first speaker is connected to the next speaker's positive terminal. The negative terminal of the last speaker connects to the negative terminal of the amplifier. When wired in series, two 8-ohm speakers add to produce a 16-ohm load. This halves the overall power going to each speaker.
Wiring speakers in parallel divides the impedance across them. Parallel wiring connects all positive terminals together and all negative terminals together. Wired this way, two 8-ohm speakers produce a load of 4 ohms. This lower impedance draws more power from the amplifier. The goal of matching the rated impedance and power for all components remains, whether wired in series, in parallel, or in some combination.