こんにちは
俺はアメリカ人と日本語は吸う。
My Japanese sucks and I'm American. Please tell me if I just accidentally said Japanese sucks...
I do not really grasp what you are trying to say.
The expression "sucks" as in, "you are bad at something" do not exsist in Japanese, but nice try though :D
If you want to say that your Japanese is bad, you say 日本語がへた
So
こんにちは
俺はアメリカ人で、日本語がへた(and usually, you write へた in kanji, so you write 下手)。
Hello! I am American and my Japanese sucks.
You do not use "と" as "and" in this context, but "で" which is a way to continue a sentence after a noun.
And I would recommend you to use politer Japanese, even if the sentence above is grammatically correct.