The link.. provides good general information on credit cards, however i wanted to know how to use encryption and decryption on credit card numbers. Form where does one start if one need to store sensitive information like card numbers.
I don't know much about this beyond a little bit of acedemic interest I am pursuing. So my comments are probably not worth a whole lot. With that disclaimer here is my 2 cents:
First you need to pick an encryption scheme. There are many different ways to encrypte data. All of these have advantages and disadvantages, so you will need to weigh them and decide which one works best in your situation.
Once you have made this decision, you need to implement it in code. If you are doing this in Java, you may want to look at the javax.crypto package. It might have a lot of tools to help implement this. In fact, it might also provide tools to help you make the decision of what encryption algorithm to use.