There are usually two ways to claim a bonus:
Deposit Code: A deposit code is usually a combination of numbers and letters that you enter during the registration process. There will be a specific field in the “form” that asks for a code. Enter the correct code and you are eligible.
Download Link: This method is even easier than a deposit code. You simply click on a link that offers registration rewards for a specific website. And presto, you are eligible to claim your sign-up bonus.