Build a wordpress website ( Partially created) -- 2

On registration page of the wordpress website (Page is created) 1)Creating the registration form 2)After registering redirecting customers to the payment gateway ( I am using instamojo) 3)After successful payment Mail the customers through our end(Mail template is ready) & return to thank you page of the website.(Thank you page is created by me) #All the data filled by customers can be exported in excel. #We want separate the list of students who have unpaid the fees and just filled the form only & who have paid the fees.