new idea, please help

Hi sir, Please i need your help and i have the following idea: * I want to build web site that can anyone register on it and then : 1- When the user login , he will create announce first, so i need to create a custom field with name,email,telephone,rubric,rubric text, select images, prise,town,city 2- After that when he fill all the custom fields , i need the important field , which is about Paypal. 3- each user must pay first to my account and then he will publish his announce, of course i will get message at he will pay to me , and when he publish his post , i will control that and approve the posting. Can do help me to fix that ? what i need to do ? which theme is good to uses in this case? Have a nice day /Ashraf