No, you cannot add vocabulary or extra lessons. Only the course creators can do that. But what do you mean by go verbs? Can you give some examples?

So my students are learning irregular yo form verbs- there are a few which have the ending -go for example- traer, salir, hacer, decir, poner, suponer, caer, and oír and the lessons only have some of those verbs. There are also some basic vocabulary that most spanish classes go over that also don't appear- such as passtimes/ hobbies/ and vacationing vocabulary. My students love this app so I want to try and use it the best I can to reinforce these topics but unfortunately I can't find lessons that encompass these.