This is very straight forward but there are a few things to pay close attention to.
If you're going to be using Paypal to accept credit card purchases on your online shop then it's best you open a Business Account. Paypal will process the payments regardless of whether the buyer has an account with them or not and they only charge a nominal fee (payable by the seller not the buyer).
1. Go to Paypal's website www.paypal.com.au and click on the Sign Up button.
2. Select the Business Account option and country you live in then continue.
3. You will be presented with a list of fields you must put your information in. Most of these can be changed later if you wish but the Business Name can't be. Extra care should be taken to ensure you get your business name correct (exactly the same as the name on your cheque book or bank statement). Later when you connect a bank account to your Paypal account (so you can transfer money to it after people have purchased your products), Paypal will attempt to make two small deposits and if there is a mismatch in the business name you used and your real bank account name , the transactions will fail. If the transactions fail your account gets blacklisted and you won't be able to use it with Paypal.
They are extremely paranoid about anything that might resemble money laundering, so extra care should be taken to get the above details right.
Please read the following questions about what to do after you've set up your account.