When your thinking of a domain name or URL address, Do Not rush into it think about what you niche market is and what you market are searching for.
This is why it is so important that you do your keyword research, after all this is your business address and your business name so it must relate to what you offering this will help you in SEO (search engine optimization) all these are covered in the pages and sub pages within this site, their are various sites you can go to and enter you keyword to see what domain it can come up with, one site I recommend you look at is www.nameboy.com.
once you have established what your domain name is you have to get that name registered with an registrar like www. godadday.com this will cost around $10 for one year but I recommend to years minimum why? because this also helps in your page ranking SEO again 
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I hope this helps you in you endeavours to online success
Go Here for help planning your website.
Ian
