Stripe Express Help

Following these instructions to add Stripe Express: https://stripe.com/docs/connect/express-accounts#token-request

I’m stuck at Step 4 (see photo). I’m not a coder, so I need a very clear explanation on the steps to take if possible. I.e. which code should I use and where do I insert it? Thanks in advance!

Please note that in this forum we do not provide custom coding solutions. Since you are not a coder, what you want to do will provide a significant challenge. Please visit our Wix Marketplace where you can find pro designers and developers to help you build your site.