Regarding contributing to sage

[Sandeep Chaubey 4-Year B.Tech. Chemical Engineering]

Hi everyone, this is  Sandeep here, I am a 2nd  year student at IIT BHU  . my passions

lies in competitive programming and  in  mathematics  .  I found immense joy doing these stuff and currently my area of interest lies in  Machine learning and artificial intelligence (doing it from past 1.5 years ) ,though I also bear a basic understanding of web development and  databases .  

I have found  expertise in  Linear algebra ,Vector algebra, probability and statistics ,statistical inference, Numerical analysis courses  . 

but I am new to this culture of open source contributions and wanted to contribute .

can I have some references or material to know more  about sage ??