I need to complete the sentences. For example: "Comme langue vivante j'apprends le..."

Right. Let's see why you can't fill the sentence. Is there any words you don't understand? Langue vivante for example. If you translare literally you might be able to understand. "Alive Language". In French we say a language is "alive" when it's still spoken like English, French or even Spanish. We call a "dead" language a language that is not spoken anymore like Latin for example. So here the sentence is : "As a second language, I am learning ..." - so what language are you learning ? French right? How do you say French in French then? Français. The sentence is "Comme langue vivante j'apprends le français "