WordPress design

Hi, I have a blog designed for marketing published articles. I need an expert who can work with me as i have done 95% of the job. What remains now is to configure the wordpress as below:

I want users to be able to “add new post” and then when they click publish in word press, i want it to redirect to my payment url. I want the configuration not to allow publish except payment goes through then it returns to the publish window or the publish goes through as new post.

I forgot to mention that in addition to above, once the publish is clicked, it takes them to my payment page on checkout.com (already done) and once they select author or contributor and pay, the system allows their post as a contributor or author according to the payment category and registers their role as such.