Need help drafting a job offer letter? List experience that relates to the qualifications as required on the job announcement.You may complete an on-line application at the Contra Costa Human Resources Department at 651 Pine St., 2nd Floor, Martinez, CA 94553. An incomplete application packet may disqualify an applicant. Learn what to include in a job offer letter and use our ready made template. We can help you discover rewarding career paths, find a job, write your resume and cover letters and even get ready for interviews. Contra Costa County is seeking talented and qualified individuals to fill clerical vacancies throughout the County!