How to pay with Bitcoin?
One of the biggest reasons why I like blockchain.info is because not only they offer web wallet, also you can download application for you smartphone and pay with Bitcoin in easy way.
When you will try to make deposit/payment most likely on screen will pop up QR code what you can scan with your phone or you can just copy Bitcoin address and pay "manually". Yes - it is simple as this.
How to withdraw it back to my bank account?
It is the same as you bought them, check website where you bought them and you can sell them later back in the same place.
Always check exchange rate, some merchants are selling
them overpriced and buying them way under market value, check real time
Bitcoin rate here.
What else you should know?
First of all you should know that Bitcoin transactions are not instant. They can take up to 30 minutes to be confirmed in Bitcoin network. Bitcoin is anonymous until some moment - until someone know that some given Bitcoin address is used by you. Yes, all Bitcoin transactions are visible in Bitcoin network, but if you have nothing to hide then you do not need to worry about that. It is important to know that there is almost no transaction fee, yes in most Bitcoin wallets you pay some slight fee like 0.005 BTC what is absolutely nothing and we can surely say that there is no transaction fee.
Bitcoin topic is so wide that it is not really possible to cover it in one or in ten articles. I hope I gave some slight insight about Bitcoin for readers who joined just now and who are not familiar what Bitcoin really is. I hope to see more and more programs accepting Bitcoin in future, but I understand that most of admins are using already developed scripts like Goldcoders and industry will move only towards Bitcoin or some other cryprocurrency only when "popular" scripts will add it in their infrastructure.