Make sure you are logged in and your account is fully set up.
Then click +Post and choose the Feed & Bedding category.
If you want to sell feed or bedding, choose the For Sale option, if you want to buy feed or bedding, choose the Wanted option.
Follow the questions through, being as accurate as possible.
Then, at the bottom click Post Listing. If you cannot press this button, you will have missed something out, maybe ticking the Terms and Conditions.