For convenience, here's the relevant excerpt from the FAQ:
Can I post a job ad?
Please do not post job ads as story submissions to HN.
A regular "Who Is Hiring?" thread appears on the first weekday of each month. Most job ads are welcome there. (But only an account called whoishiring is allowed to submit the thread itself. This prevents a race to post it first.)
There's also a "Who Wants to be Hired?" thread posted at the same time. If you're looking for people to hire, you might find people there who are good candidates for your positions.
Can I post a job ad?
Please do not post job ads as story submissions to HN.
A regular "Who Is Hiring?" thread appears on the first weekday of each month. Most job ads are welcome there. (But only an account called whoishiring is allowed to submit the thread itself. This prevents a race to post it first.)
There's also a "Who Wants to be Hired?" thread posted at the same time. If you're looking for people to hire, you might find people there who are good candidates for your positions.