building a 3S2P from scratch 18650s - how to charge?

[Ford_Prefect]

www.parts-express.com/dayton-audio-kab-be-18650-battery-extension-board-for-bluetooth-amplifier-boards—325-113

I am building similar and plan on using 2 of these in parallel.

They have a balance charger board on the back and are designed to run parallel for larger capacity.