Jennifer,
Once you pay the fee one of two things can happen:
1.) Instant acceptance. Now you have 1 year to pass the exam.
2.) Selection for audit. Now you have to send in all the supporting documents (PMI will tell you what) in order to have your application audited. Once the application has been audited & approved, go back to #1 above.
Again, take a look at page 6 in the credentials handbook where you'll find a flowchart of the process and steps.