RPi temperature "sensor" for pi-holes

I’ve got data from my dual pi-holes (both mounted on RPi4s) and I want to monitor the temperature of the RPi, but neither is the one HA is running on.

I found this guide:

…with this link in it:

I can’t figure out how to add it to my RPi “card” though, in Lovelace. I’ve edited the card, but I get either a Visual Editor or Code Editor error when doing so…and so I edited my personalized dashboard (three dots, then Raw Config Edit). My card looks like this below before adding it.and no matter how I have tried entering the code from the sample…I get nowhere. Can someone enlighten me? (I’m sure I’m missing something either basic or am totally misunderstanding where to do this…I’m not a coder…but I might learn to be one!)


      - type: entities
        entities:
          - sensor.flood_sensor_air_temperature
          - binary_sensor.flood_sensor_water_alarm_water_leak_detected
        title: Flood Sensor
      - type: entities
        entities:
          - binary_sensor.pi_hole_web_update_available
          - binary_sensor.pi_hole_ftl_update_available
          - sensor.pi_hole_dns_queries_today
          - sensor.pi_hole_ads_blocked_today
          - sensor.pi_hole_ads_percentage_blocked_today
        title: RPi 4 (77)
        state_color: true
      - type: entities
        entities: