Here is the completed version with the verbs in the correct tenses:
Dear Xenia, How are you? I have been really busy recently because tomorrow is one of the most important days of my school life - my prom night! Have you ever heard of a prom before? Let me tell you all about it! Here in the USA, the schools have prom nights every year to congratulate the students who have just finished school that year. Everyone dresses up in their best outfits and we dance the evening away in style. I have been looking forward to this day all year! The good news is that I have found the perfect dress! The prom starts at 8 so John will pick me up at my house at 8 o'clock in his new car. I am feeling quite nervous at the moment to tell you the truth. Anyway, I'll write and tell you all about the big day! Love Jennifer
If you want, I can also list just the verbs and their tenses separately for quick comparison.