Add functions in already running website

Dear Freelancer, I have a website and i would like to udapte to an higher level, i am looking for a freelancer able to realize few task for to measure your level and see if we can establish collaboration in the long term , in fact, the site I want to improve many tasks to perform and a design to rebuild completely. If the job is well done, clean code , there are no bugs so we can establish a collaboration of 12 months. Hope find my partner Best regards,