After accumulating $10 Google will send you a Personal Identification Number (PIN) to the payment address you supplied while creating account. This is a security precaution by Google to protect their publisher and it is important.
Your account payments will be on hold until the PIN is entered in your account. You can still have full access to your account and earn money, you just don’t get payment until you enter PIN. Google may disable your account if it is not entered in 1 year. I never saw any account
being disabled because of this as everyone get PIN and get payment.
Once you receive your PIN in mail, log into your AdSense account. Click on My Account tab then you will fine box to enter PIN. Enter PIN there and click on submit. PIN is also good way to check your address and make sure it is correct and you can receive checks there. Now you are on way to receive your first Google AdSense Check.