How to create a sandbox account to test the PayPal component.
When you install the extension, the mode is set to "sandbox" by default. This allows you to test PayPal buttons without actually spend real money. In order to do this, you have to create a sandbox first.
You can create and manage sandbox accounts here.
First, click "Sign Up Now" to create an account.
Then you can login by your e-mail and password.
Once you login, you have to create your first account by clicking "Create a preconfigured account". This allows you to create an account without specifying too much information. This is quite useful because you don't want to enter things like address every time you need a new account.
You need at least two types of account: a buyer and a seller. You can choose the account type on the creation page.
When you create chose two account, you can use them on your Joomla! site using PayPal Button extension.
This video explains how to create accounts and use them.