One way to easily integrate your automated tests is by using the NUnit XML output of your test runner.
You can learn more about how NUnit reports are used with Xray in Taking advantage of NUnit XML reports.
We have some simple yet detailed tutorials that explain how to integrate several testing frameworks used in some programming languages. That way, you can see how automated tests are mapped from your code to Jira.
Please check out a vast collection of tutorials in TTT: Examples using NUnit.