Struggling with learning an old-new language for myself

So, my whole life my family, me and all my surroundings was in my native(?) language - Russian,  and no wonder I know it almost flawlessly. My second language i learned was English, but i wasn't paying much attention to learning it either, it's just that when I was a kid i had unrestricted access to the internet, where almost every content was in English, so i had to adapt. As you see, I actually don't know much, feel free to correct my mistakes, it'll help me improve my knowledge! ⸜( ´ ꒳ ` )⸝

Returning to the topic of the post - now I want to learn new languages: Kazakh and Japanese. 
First because that's my actual native language and I feel kinda ashamed for not knowing it (it's also beautiful, you can listen to Moldanazar's songs to hear it, love it so so SO much!!!), and second because i really like it, it brings me joy and I also enjoy vocaloids/utauloids and want to do my own translations of songs for my covers  (⁄ ⁄•⁄ω⁄•⁄ ⁄)

And I absolutely don't know how to learn something new - like, how do you start? how do you improve? that's sooo strange to me (╥﹏╥)
Does anyone has any tips, maybe apps or helpful sites? i will be happy if you could help me, thx!!!!!! <3