Moderation!

I will move this topic to general game discussion since it is related to games as well as payment methods.

@Chris, there are two main payment systems that are in place for buying games across the internet.
The most frequently  is the money transfer service paypal.

To use Paypal you need to create a paypal account, for which you will need an email address, and possibly a street address and your name.
You can then send money in several ways.

first, if you have a debit card you can attach this to paypal, second you can directly allow paypal to take cash out of your bank, or third you can use a credit card with Paypal.
That was the option I used myself up until recently, because I did not want my bank account details on the internet, however paypal are now charging rather large commission for credit card transfers so that isn't a good way around.

Once you have setup either  debit card or bank to work with paypal you can either allow paypal to debit your bank directly with a transfer, or add money to your paypal balance as Simba described.
Note that even if you use a paypal balance and exceed it, eg, if you had ten dollars on your paypal balance and bought something for 20, you would still have ten dollars debited from your bank anyway which doesn't make the balance as useful, unless your actually receiving ppayments, though Paypal also will refund false payments pretty dam quickly and the security is extremely good so you don't need to worry too much about giving paypal access to your bank.

Some places (including Ios), don't use paypal and directly require you to have a credit card, which you should be able to get from your bank.
I would personally not advise doing any complicated credit card deals which lend you lodes of money and to keep your limit low, indeed myself I only! use my credit card on the internet and to buy things like train tickets and always pay it off as soon as I've used it.

Hth.

Ah that is cool Simba. I will need to look into my own Ios account soon because my credit card is about to expire so I might consider using paypal then instead of the new card.