Grammatically, there is no issue with what I said.
Barring the fact that the kanji for "boku", "nihon", and "daisuki" are something you should've known on your first day, you used the wrong particle for "wa".
The hiragana for "ha" is used for the particle "wa". It's a very simple sentence too, but you make it sound like a handicap is writing it.
ぼくわにほんじんがだいきらいです
What you wrote: "Boku WA nihonjin ga daisuki desu"
Interpretation: I love the Japanese people.
Non handicap way of saying it: "Nihonjin daisuki."
Interpretation: I love Japanese people.
ありがとごさいます。
You misspelled "Arigatou"