"She built her house from wood."
Translation:Ŝi konstruis sian domon el ligno.
I'll try to give the short lecture. I'd really need to build this into a table for you, but I'm not sure exactly how. So tersely:
De has the meaning(s) of "of, from, by." If you have a good dictionary (I suggest Montague Butler's fine tome, "Esperanto-English dictionary," you will find how this breaks down into logical classes.
El has the meaning(s) of: "out of, from, of (in this sense)". Again a good dictionary can break it down logically so you aren't saying but those last two have some similar meanings. Prepositions can be funny that way.
Ol is a conjunction and has the meaning of "Than." It is very different from the other two.
I'd like to say more, but I'm having computer trouble and trying to build a table showing the relations between el and de is currently not going to happen.