If you are just starting out with your online business and you have a product that is your own to sell, you will need to set up a merchant account. A merchant account is simply an account that allows customers a way to pay for your product online.
There are many services out there that offer merchant accounts. You will need to select one that best fits your needs. Some merchant accounts allow for the customer to pay via credit card, and by online check. Some will only offer the two major credit cards (mastercard, and visa) as a way of payment while others will offer all credit cards and the rest will offer something, somewhere in between. You will have to decide which will work the best for you.
Here are a couple that you may want to consider. The easiest one to setup and start using right away is paypal. PayPal has been around for quite some time and now offers merchant accounts for most countries. In the early days they only offered their services to US residents. Now just about anyone can open a PayPal account. You will need to have a checking account to use this service. You will also want to get verified with them as well. While this is not required for your merchant account it is however necessary if you want your customers to trust that you are a legitimate online business. You can read more about getting verified once you have registered for PayPal at https://www.paypal.com/cgi-bin/webscr?cmd=_registration-run They only offer Mastercard and Visa.
If you'd like to go another way, clickbank may be the answer. Clickbank is a marketplace where your product is displayed on their site along with other merchant's products. People will pay for your product through your clickbank hop account. You can read more about clickbank by following this link. clickbank.com
The above two are free to join. You will have to pay a percentage to the merchant account service for each sale that you make. You only pay when a sale has been made. They will all be different. You will need to read what percentage they will charge from their web site. If you want to get a larger list of services that offer merchant accounts you can alternatively run a Google search.