Hi,
1) did you check out the documentation? what are you trying to achieve with persistence? if you have a long running process, the documentation should help you to get things set up.
Are you using maven? can you share what's the problem in your project? what do you mean with is not working?
2) You have different options:
a) Do you really need to draw your retrying mechanisms? Is it relevant for the business? or is just a technical detail?
If it's a technical concern, you should probably better not draw it in the process file and delegate that logic to the work item hanlder that is in charge of that interaction.
b) you can model it in the diagram using gateways
Cheers