Tax for Affiliate Marketing in US ?

Hi all,

I just completed my engineering. I owned some websites from long time and I earn money from affiliate marketing. I used paypal till now . I have a office with no board display or trade name. I have 10 employees to maintaing around 50 websites all earns from affiliate marketing. I am getting paid from US - paypal / wire transfer / check.

I dont know anything about tax even the ABC. Just got PAN card. Please help me. is tax applicable ? And What i need to do to make me safe in future.

Thanks in advance.

J