To setup your company page, you can make a page from "Pages" > "New Page" section. Afterwards, you can post job listing from "Jobs" > "New Job" section and link your jobs with your company page.

To apply for a job, first see what are the current job openings from "Browse Jobs" section and then open particular job profile and click on "Apply Job" button. 

To post a job, you just need to have an account on the website. After that, you can post a job listing from "Jobs" > "New Job" section.