Small enquiry

Hello Every buddy

I have a small Query ,Suppose i am a small trader who buying thinks from small shops from where i can not get bill and i sell it online .and i have monthly transaction for this is 50000-100000 in my bank account to which my pan card is attached.I have not filed any return as i have started this small business last month so how can pay taxes and avoid any problem from income tax department.

PLEASE REPLY.