Need Guidance

[palSayan1000]

I know java but i have open multiple repositoris and did not understood anything I want to start building and start with open source can any one please guide me
I am from India in sem 1 of college one month have just passed. I see hackathons happening everywhere i am eager to learn contribute to open source. Such things when opened for the first time are very overwhelming. It would be very help full if any one could guide me