I'm sorry if this is a repost, but I personally find it really odd & annoying that you don't learn the infinitive of the verb when you learn the conjugations.
I can say "I want" and "I drink", but because the infinitive is not introduced, I can't say "I want to drink" (well I can, but I know the infinitives...).
I've had to supplement most of the verbs and look up the infinitives on my own - irregular verbs are the most troublesome, because they can't be guessed.
Just my two cents. I was really surprised a few weeks when I realized, in the middle of a conversation, that I couldn't remember how to say "to go"!
Check out your vocabulary page. When I go to mine for German, I see that I know the different forms of lernen, and then I can go to this page: http://duolingo.com/#/word/de/lernen/Verb where it gives me all sorts of details about conjugating the verb, the different tenses, etc.
Hope this helps!