Many companies prefer to use local businesses for their website development. This makes it easy when it comes to discussing ideas and pass material between the two parties. Firstly you will need to find a web developer that can produce quality work at a price you are comfortable with. It may be that you chose a freelance programmer to keep the costs down over a web agency.
Most people look for web developers online through search engines such as Google or Bing and with the localised results often showing first, it is easy to see how far these people are away from you.
Once you have found a few developers, be sure to look at reviews and also examples of previous work they have completed. If you are happy with what you see, then get in touch and arrange an initial meeting. I do not know of any agency that charges for this initial meeting so you could meet with more than one to get an idea of what each developer can offer you.