Stripe is a developer-friendly way to accept payments online and in mobile apps. They process billions of dollars a year for thousands of companies of all sizes. You can make payments by credit card or with bitcoins..
You need activate your Stripe Account.
Copy your Stripe Secret Key and Publishable Secret Key from Your account -> Account Settings -> API KEYS
4.Finally return to your store's,Admin Panel > Settings > Payments,add Stripe payment method and replace the fields.