Step 1
Go to www.ads.google.com to set up your AdWords account. Crate it under your existing Gmail account or create a new account.

Step 2
Set up your time zone and currency preferences.

Step 3
Set up your billing information. You will get two payment options: Automatic and manual payments. Automatic payments allow you to after few clicks. You will be charged once you reach your billing threshold or 30 days after your last payment. You have to prepay in manual payments, and a charge will be deducted from your prepaid amount. Your advertisements will be suspended until you pay next if your balance diminishes. You can select either of the payment options according to your wish.
