The "submit for approval" button is at the bottom of the screen (see screenshot attached) when you are within the job post (you must scroll to the bottom of your job page and then you can hit submit.)
If you have logged out/do not see the button at the bottom, click on "Edit" in the bottom of the job page (by Skills section on the left) and then go through the final 2 stages ensuring all is correct by clicking "Save + Continue" for the 2 stages. Once you have done that, the Submit for Approval button will reappear.
The final step, if you have not already verified the account, will direct you to a verification page. You can enter credit card information or you can click on using the referral code and enter in your code from the The Second Shift Business Development partner.
Here is the sign up video as well (at the 2 Minute Mark, it will show you these steps).