Phrases: Leo has introduced a database of fixed expressions and phrasal verbs to the Jungle. Now, if a word is part of fixed expression, other word/words that form the fixed expression are highlighted when you hover over it.
When you click a word like this, the first thing you'll see is a translation of the entire phrase, but you will be able to translate the individual word as well. I recommend studying and understanding text with the help of fixed expressions.
But if you want to translate just 1 word, click on it in «Word translation».
Sentences: to add a whole sentence, put your cursor over it and you'll see a blue rectangle with dots at the end:
Click on it and you'll see a window with the translation options. Select/enter a translation, and the sentence will be added to your dictionary.