They are not addon’s ( these are ) they are integrations.
Select the one you want from the page you linked to and it will take you to an instruction document for configuring it.
For example, I want to add the weather darksky.
Add to my configuration.yaml file
weather: - platform: darksky api_key: MY_API_KEY
But nothing happens, maybe something else needs to be done?
Did you replace
MY_API_KEY with an actual API key you created as per the instructions?
Of course replaced
Understood, I did not restart HASS
Now everything works