You have to login in order to submit a listing. You can login if you have an account. Accounts are free to register.
To register click on register, then a page with a registration box will open. Enter your username which can be your real name or a nick name which you can remember. Then your best email address because the password will be sent to that email.
Open the email you will receive within 5 minutes with password setting instructions. At this point you are good to login and post your first listing.