Hi, it depends, can you give us more information, like is it for mac, windows or linux. And you need to think of a way to deliver your crypter. It is not that easy, there is no general answer to that , each system is individual, meaning maybe it is already patched, so no known cve's. The first step is gathering information about your target, then you can prepare an attack which is designed for your target. If you wanna find vulnerable systems go to shodan.io.
Short answer, there is no answer. Learn the basics first.