If you don't claim the offer at the time of your first deposit, you can do so at any time within 30 days of registering your account. Simply log in to your account, go to the Account menu, choose My Offers then click Claim Now for the relevant offer.
To claim your Free Bets simply select the claim button when making your deposit. Alternatively you can claim them in your My Offers section within 30 days of registering your account.