On Netflix I think

All the animated series are on Netflix, and you can find all the classic animated movies in various spots on the web for free. Not sure where to watch the live action one though

It is really good, once you watch it you never go back. However, I advice you to start with watching Barbie epic road trip first, hence some dreamhouse adventure episodes may be plain (but they have really good episodes I recommend it)! You can watch it on Netflix

It would be bet to watch in order (all the way back to 2001's Nutcracker) But if you are only interested in the modern dreamhouse adventures universe, the real start is Dolphin Magic, then Dreamhouse Adventures, then Princess Adventure then you can go on to stuff like Big City Big Dreams. It would be weird to watch Epic Road Trip without seeing Brooklyn's introduction movie.