System testing ensures that the software is fully integrated. The primary goal of system testing is to evaluate complete system specifications. Functional and non-functional testing are both included in system testing. If you are planning to break into the Software testing domain, and not sure where to start, I would recommend you start by enrolling yourself in a test architect certification, from Intellipaat. This training will provide you with all the necessary skills and help you to become a certified tester.
Before that do check out this software testing tutorial video by experts at Intellipaat -