Sometimes, you may want to wire batteries in parallel.
The reason for that is you want to increase the battery pack in current. Wiring batteries in parallel will sum the current from the two batteries.
Below is schema of how you can connect your batteries.
Beware that your batteries have the same voltage; otherwise a balancing of your circuit will occur. The battery with the higher voltage will attempt to charge the battery with the lower voltage. Be sure that all of your units are fully charged before connecting them.