I know that 由 means
from but I'm not sure exactly what contexts to use this in. For example the dictionary has this example sentence:
I understand this but I would have used a sentence like these:
I'm trying to get more familiar with when to use 由 and to incorporate it in my verbal interaction (otherwise I'll probably never use it and forget it). I realize the three sentences above are very close in meaning, but I'm not really sure how to understand when, where, and why I should use 由.