I agree with Prashant and would like to add some parameters that may help you think forward while preparing the JD.
Job Description
A job description refers to a list of duties and responsibilities of a position. It may often include to whom the position reports, job specifications such as the qualifications or skills needed by the person in the job, and/or a salary range. Job descriptions are usually narrative. A JD is usually developed by conducting a job analysis, which includes examining the tasks and sequences of tasks necessary to perform the job. The analysis considers the areas of knowledge and skills needed for the job.
Also, you can find numerous sample JDs if you research [Find this tab in the top left corner] on this site and/or Google.
Regards,
Asif