Yes, you need to have a certain number of posts first. Posting for sale does not count as posts. We a must be contributing in other ways than just trying to sell. Once you get that under your belt, people will know you better and you shouldn't have any trouble even with just pictures.
Just remember, the classifieds is to help, not run a business. I just looked thru your posts, and your very first post was asking how to sell fabric.
Good luck! And welcome to the quiltingboard, glad to have you! :)