stripe is not processing charges

[jserodio]

I'm starting to understand how Gatsby and still fail to understand how this completely work.

My main goal is to upload it to netlify, use netlify login to access the admin site and use netlify cms to edit or add items.
Then I would like to process every payment and create invoices with automatic mails with stripe.

First things first, I want to proccess the payment for a simple sofa and I'm having a little trouble with it.

When testing the website after gatsby develop, I don't see the charge at stripe dot com.
I'm using the testing publishable key.

In stripe the only thing I see is an API call to:
/v1/payment_methods

But I can't see the charge in payments, nor the item details in the call...
Is it necesary to use the lambda.js?
And how exactly could I run lambda.js? is it a node.js code? do I need to upload it as a micro-service elsewhere? I figure I should add the secret API key there but is it really necessary?

For now I'm just testing everything locally.

Thank you so much, this is looking too good. Any help or advice will be much appreciated.