You can assign one ore more states to each page. Based on the status of the records, the users get access to the corresponding pages.

For example, define portal states, such as registered, submitted, approved, rejected, and sent back. When a supplier signs up, the record is associated to the registered state. The supplier will be able to see pages that are associated to the registered state. If you associate the registration page to the registered state, the supplier can access the registration page to submit additional details. After the supplier submits additional details, the record is associated to the submitted state. The supplier will be able to see pages that are associated to the submitted state. After the record is approved, the supplier will be able to see pages that are associated to the approved state.