If you're already paying taxes with your full or part-time job and you tend to get a refund, you may not need to pay quarterly taxes. On the other hand, if you usually break even when you file your return, then it might be a good idea to make those payments.
I would recommend filling out Form 1040-ES here anyway to find out for sure. This will essentially compare your full-time job to your self-employment work and help determine whether you need to submit quarterly payments. It's a little extra time and math, but will ultimately give you the best answer!
Stride has whipped up a step-by-step guide for filling out Form 1040-ES here: How do I file estimated quarterly taxes?
If it turns out you do owe quarterly taxes, you can find instructions on how to get started here.