Don't worry! If you just signed up for a membership, but still can't get member-only items here's a few things you can do: 

• Log out of Club Penguin so the system can update your account, then log back in. 
• Depending on what type of payment was used to buy your membership, it may take a few days for it to activate. Visit How soon will my membership take effect?, to see if your membership needs time to update.
• If that time has passed and you still don't have your membership, ask an adult to contact Club Penguin's Billing Team, they'll be happy to help you!