To have an online store, the easiest way is to find a script open source e-commerce. For example oscommerce or zen cart shopping cart. Get these script setup your web hosting.

To accept online payments, or pay its customers through its website, or customers via website payment gateway and payment. Selecting which one, depends on your needs and budget.

After merchant third is the lower cost and easier. You can register with payment processing or paypal or 2checkout payment processing VeriSign. And the route customers to the ratio provided by them. Customer will pay in the provider's web page, and once its done, the client will return to your website.

Be sure to choose only those famous third largest traders who do not trust those you find on the internet and offering incredible low cost and no fee solution. Who knows, you will not receive their money in the end.

Whether you can find a web hosting provider that offers merchant account as well, and that will handle all the integration work for your ecommerce store.