Newbie - Configuring customize,groups,devices

I’m new to HA, and just getting into it.

One thing I’m having trouble grasping is where the device names come from that are in the customize section of the configuration file.

Say I have 2 temperature sensors, defined as sensors in the config, with names “Temp 1” and “Temp 2”

how do I group them together?

To find out entity names, go to developers page ( < > button), and on the right column you’ll see all entitys that HA recognizes.