how and where do i start if i am completely new to the japanese language?
my first language is mandarin
If self-studying, the translation and grammatical explanation notes for Minna no Nihongo is available in Chinese. It would be easier to transfer to a school using Minna no Nihongo at a later stage.
In any case, your first language should not matter when studying at a school like Ikoma as the teachers only speak Japanese in class.