To integrate your online ordering store with Braintree Blue, you need to get ;
Your keys are unique pieces of information specifically associated with your payment gateway account.
1- You'll want to enter this by going to Settings>Order Payment
2 - Choose Braintree (Blue) from the gateway list
3 - Enter your keys, check off what card types you want to accept, select the order types that you want to collect tips on & hit Submit at the bottom of the page.