How do I have an apple ID?

If you've posted on here then you have an iTunes account/Apple id. If you want to create a new account then there are instructions on this page for how to do so : http://support.apple.com/kb/HT2731

Or if you want to create a new account withoug giving credit card details then follow the instructions on this page : http://support.apple.com/kb/HT2731