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.
Then to activate your account please fill out the details on the following page.
Next you have to copy your Stripe Secret Key and Publishable Secret Key by clicking on API on the left side bar
Finally return to your store's,Admin Panel > Settings > Payments,add Stripe payment method and replace the fields.