I think you are mixing 2 different concepts here:
- Create different versions of the same Process: currently jBPM5 doesn't support multiple versions of the same process. If you want to have a new version of a process you need to use different ids. Please read the section about process migration in jBPM5 documentation.
- Versionate process definitions: this means that process definitions (.bpmn2 files) are versioned like if they were under a version control system. If you are using web designer, you already have a version control system in Guvnor. Every time you save your process you are creating a new version in Guvnor's repository. If you want to move between versions you can use Guvnor to do so. Please refer to Guvnor's documentation for further details.