You can configure the shipping and the payment methods
for your script through the admin area -> System ->
Configuration -> Sales:


In this tutorial we will illustrate how to enable the
USPS shipping method and the credit card payment method. The
others can be enabled using a similiar approach.
Before enabling the shipping method please configure the
shipping settings:

The fields there are self explanatory.
Once you
are ready, please click on the Shipping Methods -> USPS
link:

Enable the shipping method, enter the Gateway URL and the
UserID. The next options allow you to describe the packages,
which you need to be delivered. Then you can define the
handling fee. It can be fixed or calculated on the percent
basis. After this you can pick the allowed delivery methods.
You can configure a free shipping method and define whether
there is a minimum purchase sum for it. At the end you can
define the countries for which the shipping is supported and
the default error message in case the service is refused.
The credit card payment method can be configured through
the Payment Methods -> Saved CC section:

Enable the method, enter its name, set the new order
status, pick the supported credit cards, decide whether the
credit card verification is required, define from which
countries to accept payments and the range of the accepted
payments. Then you are ready with the configuration.
We hope this tutorial will help you get your new online shop
ready. We wish you good luck with your project!