"Because it was scary, I cried."
While からis fine too, I feel のでis more natural here. からhas the meaning of "since", but for explanatory purposes ので works better.
There's more of a nuance to it, actually. ので places emphasis on whatever precedes it, while から emphasizes the following resulting action or request.
こわかったから、なきました。Because it was scary, I cried.
こわかったので、なきました。I cried because it was scary.
Pro tip: With requests, it is seen as more polite to use ので:
こわいですので、かえりましょうか？(since it's scary, can we go home?) is more polite than こわいですすから、かえりましょうか？(since it's scary, can we go home?)
Placing emphasis on the reason, as opposed to the request, will soften the request, while から will make it seem more demanding, so be aware of your status among those around you and speak accordingly! Being aware if this detail will also help you sound much more natural when speaking :)
Isn't it that in sentences with more verbs only the last is in the past tense?
怖かった is a past inflection of 怖い, changing is scary to was scary
This one didnt make any sense to me at all. Is there any websites where i can get extra resources?
I don't use anyone specific resource. I like to search for my specific problem and consult multiple resources when I don't understand something. Wikibooks is a good resource and so is Youtube depending on if you want written out or verbal explainations