Je viens d'Adelaide. -- I come from Adelaide.

What was your question again?

When we say J'habite we use 'en' (I live in...) and coming from we use de or d'?

In the case of habiter the preposition depends on whether you refer to a country, a province or a city.

J'habite en Australie.
J'habite dans le Yorkshire.
J'habite à Paris.

But in the case of venir, it is always de: Je viens d'Adelaide.

And then there is the gender of the country. Most countries are feminine and use "en" with habiter. But some are masculine and require à: J'habite aux États Unis.

Here are two related lessons: Using en with feminine countries and au(x) with masculine countries to say in or to (prepositions)

En, dans = In, to with regions, states, counties (prepositions)

merci beacoup!