How to receive payment online
When selling online, you will need to setup a payment platform that works for you such that it holds your money in an account soon after sales have been made. You can setup payment platform that accepts credit or debit cards, ATM cards, iWallet, G-Switch or even global tools like Payza or Liberty reserve.
How to deliver sold items
For most items which are virtual or non-physical, you can grant access to buyers to download them or password to start using the service online. For physical goods they would have to be delivered physically using a courier service after payment has been confirmed.