According to the manual, the JBL charge speaker has a small port in the bottom center below the JBL logo. This port connects to a charging cable that plugs into an AC adapter.
The power port to charge the speaker is at the bottom center, directly next to the circular port that connects to the headphones port on a smartphone. The side of the speaker also has a USB port to charge another device from the speaker.
There are three small lights next to the power button on the JBL charge speaker. If one light is on and flashing red, then the battery needs charging. Otherwise, there should be one, two or three lights that show a continuous blue, representing if the speaker has low, medium or high power in the battery.