If you do not know about Stripe Gateway, you can read this manual to learn about it. Stripe Documentation There you need to create account, I have already created this account. If you also created Stripe account, then install Stripe.
After that, click on the settings button.
Here you have to put your Publishable, Secret key and Signing secret. You can get them from your account.
To get Signing Secret, put your webhook on your webhooks and get your signature secret
if you put your webhook, just go inside, and there will be your secret signature, and click here to see your secret.
After that, click "Save" to save the changes. That's all! your payment gateway is ready for testing.