You may complete an on-line application at the Contra Costa Human Resources Department at 651 Pine St., 2nd Floor, Martinez, CA 94553. Need help drafting a job offer letter?An incomplete application packet may disqualify an applicant. List experience that relates to the qualifications as required on the job announcement. Learn what to include in a job offer letter and use our ready made template. Contra Costa County is seeking talented and qualified individuals to fill clerical vacancies throughout the County! We can help you discover rewarding career paths, find a job, write your resume and cover letters and even get ready for interviews. Next you complete a series of steps (entries or screens). Many schools offer career-guidance tools. These tools can assist you in finding out how your interests and skills fit with careers and college.