[ryuurui]

it's simple, you need to learn the words. First learn the hiragana, and then learn Japanese words. It is "kodomo ga", not "kodo moga". "Kodomo", in hiragana こども, means "a kid".
Japanese is a homophonic language, meaning, various words may sound identically. This is why we have kanji in Japanese. You learn them after you are done with learning hiragana.