The site will give you names and phones numbers for designers that specialize in residential design and that are located in you area. Also, consider hiring a student designer. Contact one of the local design colleges or the university's and ask them if there is a job posting board in the facility. These students have a lot of creativity and energy for smaller jobs. E-mail them and request their pamphlet on How To Hire a Designer.
Designers usually charge by the hour.
In addition to the hourly charge, there may also be a fee or percentage added onto to items purchased by the designer for your project and to any work done by other trades in your home. The designer will usually charge a retainer and then asked for progress payments as the job progresses. When you are setting up interviews with perspective designers, ask them ahead of time if there is a charge for the initial interview or not. This will very with each firm and individual designer. Choosing a designer is an important job.