Go to https://stripe.com/ and click the create account button.
Add the desired login details you want to use for stripe.
Once into your dashboard you need to make sure you have verified your email address with stripe through email.
Now back on your dashboard you can fill out your company details to activate your account.
Once complete, head to the developer section and select API keys.
Simply reveal and copy your live secret key.
You can now enter your live secret key into the payments section.