As stated in >Emitter Editor UI Basics the light editor is activated by pressing the light bulb button () the tool’s top menu, or ALT + F2 on your keyboard.

The top menu is the same as with the Particle editor section so refer to that if memory fails.
The differences start with the main menu:

• Light params
• Directional
• Save Preset
• Load Preset
• Export
• Special
• Prefs (this is the same exact “Prefs” as with the Particle Editor)

For the Light Editor main menu the keyboard shortcuts range is CTRL + 1 – 7.
The Prefs leaf is the same as with the Particle editor, there is no Light editor specific preferences.

While Light editor selected pressing INSERT will insert a single light emitter with the default name of light_emitter_X.

By default the emitter emits no light so all the parameters are empty.