Can anyone guide me for getting the job in qatar

what are your qualifications and skills?

Ask first your employer if he is ready give NOC to work to other company if yes then, Search job as early as possible go visit company personally, when you will get new employer will proceed for new visa

If your work permit is expired recently and you need to change job, you need NOC from your present sponsor. then when you find a new job, your new company will process your new RP.