Lighting the heater

[Gabby1987]

Purchased 331 rl in the spring and with the weather cooling off I thought it would be a good time to make sure the heater works. We previously owned SOB and the heater was in a lower cabinet, however, I can't find it in any cabinet in this model-I know things have changed and improved since the previous unit. Nothing included in the owners kit concerning lighting the heater. It may be a stupid question but can someone point me in the right direction?