Running Process Instance, shifting and continuing

Hi,

I am trying to make a shift on a running a process instance and continue the process from the new Activity/Task/Event.

Is there a way to achieve this?

runtimeService.createProcessInstanceModification(processInstance.getId())
    .startBeforeActivity("activityId")
    .execute();

I am using this code block to achieve shifting and what else need to add there?

And, How to identify an activity id from a running process using the activity name?

Thank you.