i finished the tree, are there other tree for learning ?
First of all, congratulations!!!! Second of all, if you completed the english-from-spanish tree, and if spanish is your native language, then there are the options of learning portuguese, german, italian or french (all from spanish). Hope that helps! ;D
Another option, if you want to study English further, is to do your 'reverse tree' now: select "I want to learn Spanish (I know English)" instead of "Quiero aprender inglés (yo sé español)". That takes you through all the lessons, but backwards - and you can read discussion threads about the questions that are almost entirely written in English.
Or, as galletanumero66 says, you can pick another language!