Email to my Japanese exchange student

I'm writing to my exchange student but my Japanese is less than stellar. Any suggestions for grammar, spelling, or if I should write anything else would really be appreciated.
This is what I have so far:
こんにちわかなとくん、
わしの なまえは Elaineです。こうこうのにねんせいじゅごさいです。
これはわたしの かぞくです。。(I will attach a presentation I had to make in my Japanese class about my family)
よろしく おねがいします。
Let's have fun in America together!
Elaine

It's じゅうごさい. Technically you should also write こんにちは, but こんにちわ is in sufficiently wide usage, especially by females, that it's probably fine.

Apart from what has been mentioned by Firas, in the sentence about your name, you happen to have わしの instead of わたしの to say "my." For the rest it is fine :)