At the beginning of each lesson, there is an introduction, but it is only available on PC's. Click on the lesson circle, then click on the light bulb icon. Memrise.com has a short Hebrew alphabet course for Duolingo. You can also google "learn Hebrew alphabet". There are a number of resources on line. YouTube has some things as well. Amazon.com has some books for learning the Hebrew alphabet, too.
Can anyone tell me how in the world I am supposed to be able to read Hebrew instantly?! This app seems like nonsense, especially when Im asked to even write in Hebrew. How??
I think you mean את and אתה not אח and אחה (though both of these are also Hebrew words). Notice the difference between chet ח and tav ת. It's good to read all the comments first. You might have found the answer to your question in others' comments. Both mean "you". את/aht is feminine and אתה/ahtah is masculine.