Independent Contractor Taxes

Hello,

In March of 2018, I was hired as an independent 1099 contractor. I have never worked one or paid taxes myself. I was paid $5000 in June and $11000 in September. I know I was supposed to pay taxes quarterly, but my friend told me since I have not made that much, even if there's penalty, it won't be much. But now I am concerned. How do I calculate the estimated taxes? I bought a computer and other office furniture for the job. And I had another part-time job meanwhile, which only paid $300-$400 a month. Thank you in advance.