Hi @JiwonK16838398: If these are different process in the case designer, hope you will have different process configured in the stage after completing a specific step. In this case you can configure when rule / expression in each of the process (Click process, in right side general tab, you will see Start process. Select a when rule / expression and give condition based on the dropdown selection). Please see more details here.

If you are working within the process using sub flows, you need to add a decision shape. Once you have the decision shape available, you have multiple options to configure the flow path. In this case, you can use a fork / when rule to define the flow path. Please see details here.

Thanks.