which one?

in mangas, there is a mixed between kanji and hiragana.

It's a mix of kanji and hiragana. But you should know katakana as well, since it comes up for foreign words. Shounen manga or manga aimed at younger audiences tend to use furigana along with the kanji so you know how to read it.

It's a mix of all

You need to learn all of them. Start with hiragana, then katakana, last kanji.

aww i was hoping this would be easy hahaha but do u guys know any websites that offers free lessons?

google translate only works with words, not full sentences.

https://ejje.weblio.jp/
Is a good site for learning words. It's a dictionary of sorts.
The best way to learn the language is actually getting real lessons. But here is a few videos.
https://www.youtube.com/watch?v=6p9Il_j0zjc
https://www.youtube.com/watch?v=OPbnF6vEkWs
https://www.youtube.com/watch?v=OPbnF6vEkWs

oh and you HAVE to learn the grammar. Some sentences won't make sense otherwise.

lol unfortunately learning a language takes time and practice haha

here are some good sites to use to learn some grammar
http://www.guidetojapanese.org/learn/
https://www.imabi.net/

This site is also helpful in learning grammar but might have to pay after a certain level, not sure.
https://www.bunpro.jp/

This site helps you learn and memorize kanji but you have to sign up and I think only the first three levels are free.
https://www.wanikani.com/

This helps you learn hiragana and katakana
https://www.hiraganaquiz.com/
https://www.tofugu.com/japanese/learn-hiragana/
https://www.tofugu.com/japanese/learn-katakana/

Also if you want, you can pm me and I can give you some links to download some helpful textbooks I used to learn Japanese as well.