How to pay income tax?

Hello, 

I work for an small company which gives salary by cheque. They don't have any provision to deduct taxes beforehand. I joined in July 2014.

How do I pay my taxes from my salary. 

1. How do I pay my taxes? Online?

2. What is the cutoff time to pay my income tax? 

3. How do I calculate? 

Please help! 

Thanks!