Change publish process on classified ad site (OSClass CMS)

Hello! Site: [login to view URL] I want to change the publish process so it looks like this: 1. Click on publish ad button 2. Write all information about the ad, upload pictures etc 3. Pay with Paypal (Or with pre-bought credits) and Register with e-mail adress or log in to existing accout If payment is successfull it should automatically post the ad. Most of the things are there already and just need to change order of how things flow. There are few other minor things I need help with on this project. If you finish this one task successfully there will be more work for you.