My grandmother wanted me to learn german

My family is first generation American having immigrated here from Germany. My grandmother is very tied to her german roots and wants me to learn german. She has always spoken german to me and my sister but I have a very broken understanding of the sentence structure and the tenses. I can understand bits and pieces but not enough to carry on a conversation. Nana bought us tapes to listen to that will give us the equivalent of a first year of german course. She will be so thrilled when we can hold a whole conversation with her about anything.