Well ya, someone has just explained but I would like to say a little bit more.
Kore, Sore, Are stand alone and they always refer to something, just like This and That in English.
When attached with a noun, in English we still use This or That but in Japanese you use Kono Sono Ano + noun.
Everyone has a hard time learning the kana... my way of learning is listening to Japanese anime song while staring at the lyrics at the same time
Gradually I memorize all the kana with no problem at all.
And yes it's better to learn kana as early as possible before you start learning anything else... 'coz it's really painful to express Japanese in Romanji (= Japanese kana in English alphabet). And you need to learn kanji too......
Oops sounds like I am scarring people away......