PayPal has updated its button integration into the websites. This new PayPal smart checkout button is looking modern and user friendly. It is also easier to integrate in any website without doing much coding. You only need to copy and paste the code and you are good to go with the payment. You must have a PayPal account and for testing you need to create a sandbox account where you will be getting test amount which you can use to do the testing of the code which you will have implemented. Once testing done then you can switch to live mode and there you will able to accept the actual payments from your customers.
For testing in test mode you needed two accounts to create one will be merchant or business account and other would be personal account. You will have to put the secret ID of your business account inside the code where the payment would be received and on the other hand you will have the personal account which will help you to do the payment and the amount would be deducted from there and increased into the business account once the successful payment would be done.