The CMS does NOT directly integrate with or interface with your payment processor.

If you have a single join URL you can enter it in your tour admins JOIN URL  setting for your tour. This will link up all join links to use that URL.

If you wish to have multiple payment processor options(Credit Card, Check, Phone, TEXT/SMS) then you'll need to edit the join.tpl file located in your theme area.

Included within your cms templates within

PHP Templates:

/cms_admin/phptemplates/[templatefolder]/tour/join.tpl

Within this template, you'll put the URL and text you want to display for each of the payment options. Take a look at the join pages of some sites and get ideas. Your payment processor will install their script to manage users and should be able to give you more info on the join forms and such. If you need help with customizing this form, let us know and we can recommend 3rd party coders and designers to help you.