Registering on the website
It's simple, just go to the "Your Account" tab at the top right of the page, and click on "Register". You'll be asked to choose between registering as a regular customer or a trade customer, buying for a shop - check the "Buying for myself" box unless you're buying for a shop or business.
You'll be asked for some basic details, including choosing a password, and once you submit you will then be registered on the site, and ready to place an order!
You don't have to register to buy from the website, you can checkout as a guest, but if you are planning to buy more than once it may just save you some time on later orders!