[だ]から : so, therefore; since, because
なぜなら[ば] : because (なぜ meaning 'why')
our examples are:
英:I brought an umbrella because it's raining.
日:
日:it's raining - because/so/therefor - [I] brought an umbrella
英:There's clouds - therefor - seems like rain.
英:seems like rain - because - there's clouds
日:
This may seem fairly obvious/natural but to emphasis the "head last" nature of Jp here's a sample question answer:
英:Why did you bring an umbrella?
日:
英:Because it's raining.
日:
Now go back and read those examples :)