E-Commerce
If you want to set up a website to sell goods or services online, this would be known as an e-commerce website.
To accept payment online, you need to have an account with a company who will process the payments in real time. Many companies exist who will handle your online payments, and there are pros and cons to each.
A lot of e-commerce websites will use a 'gateway' service like WorldPay for this. You should visit their website to find out all the details. Annual fees can be expensive if your sales are not high to start with, and you will find yourself dealing with your bank in order to get the right kind of account for this sort of trading.
Very popular is PayPal . They offer a service which has no ongoing fees and works very well for a business whose turnover is small. It is very simple to add the PayPal shopping cart to an existing website, and you will find some of my clients use this service.
I can also offer a free shopping cart with which you process your own credit cards with your PDQ machine. Great if you already have an account as there is nothing special to set up - buttons can be added in minutes to an existing website with no modification. You collect the card details from the included secure server and process the sale when you are ready to supply. This also helps stop costly chargebacks from items which become unavailable. The system can be upgraded to a wide range of online payment processors at any time in the future for a small monthly fee (currently £10).
I will do my best to advise you as to which course of action you should take, as there are too many options and variables to list here.