Japanese colors - Kanji or Hiragana/Katakana

Hello!

First of all, I'd like to mention I'm learning Japanese just two days but I'm getting into it pretty fast I think. I'm learning colors atm and I see there are both Kanji and Hiragana/Katakana versions (obviously). My question is - which one of those are more used and which one of those are worth learning? Or should I know both? Or just Kanji? Thanks a lot!

It totally depends on the color or the situation where it's used. Kanji is more common when the kanji word is common (e.g. 赤, 青, 白, 黒), hiragana is preferred in books for children even for these colors, katakana is often used for the name of plants (菫色 vs. スミレ色), etc., etc.. You'd better to learn kanji if it's in joyo kanji.