Actually, there are quite a lot of comprehensive basic explanations on the web, for example, these ones: <a href="http://learnrussian.rt.com/grammar-tables/verbs-of-motion/">http://learnrussian.rt.com/grammar-tables/verbs-of-motion/</a> or <a href="http://www.russianlessons.net/grammar/verbs_motion.php">http://www.russianlessons.net/grammar/verbs_motion.php</a>;

As for the sentence, you've provided as an example, it contains an error — see Denis's comment.

When did you go to Siberia?  Когда вы ездили в Сибирь? "Ездили" is used because of "where to" —  "в Сибирь" = one-way action.

Jessica, "ехать" is close to "to be going/driving".
It means heading to your destination in a particular moment or over a time span.

It can confuse you in "we drove six hours" because in such cases we use "ехать" as well (because over many moments of those six hours we were headed to our destination, sort of, "kept driving").

One of meanings of our imperfective is "experiencial": we use it when speaking of having experienced something.
It doesn't matter how many times, it only matter that you have this experience. E.g.:

Ты читала Властелин колец"? - have you [ever] read Lord of the Rings?  You may add "ever" if you like, "ever" is a clear sign of this meaning:)

With verbs of motions we use the "multidictional" one for this meaning.