How to go about charging users for recuring subscription payment

once they submit the form, how do we go about charging them for the subscription since there's no place for them to enter their Paypal information for the reoccuring subscription.

Please refer to our user guide : How-to-Setup-a-Recurring-Payment-Option

The billing information of the user should be captured already on their initial payment. The Paypal payment screen will be available to the users once they submit the form.

The user will be able to provide their payment details then. So there is no need get again the same payment information for the next recurring billing/payment.

I hope this is clearer. Let us know if you need further assistance.