Finished my tree!
I finally finished my Spanish tree! Yay..... So what do I do now? How do I start the reverse tree?
After finishing the tree, keep the tree gold for a bit, to let Duolingo's spaced repetition algorithms help you revise the stuff you've learned. At the same time, start reading You'll need to give us more information if we're going to be able to help you. What is it you need help with? children's books, and listening to children's radio programs. If you can get a book and audiobook of the same thing, that can really help to improve both your reading and your listening skills.
A lot of people on these forums recommend using Memrise courses to expand your vocabulary, and Lang-8 for improving your writing skills.
You'll probably also want to find someone to speak You'll need to give us more information if we're going to be able to help you. What is it you need help with? with. Have a look at this post about how to find language exchange partners: https://www.duolingo.com/comment/1444346. There are links to some useful websites on there. Don't miss DamedesLangues's comment, which has links to more sites.
It's also worth looking on the Multilingual learning resources page on the Duolingo Wiki.