Welcome!!!
ECCIE doesn't allow ladies to post "ads" per se, like other sites. You can however post and participate in social threads - which is a signal to others that you're in the area and one could infer you're "available" based on that.
However; there is a thing called a "Bio page". Ladies can put information there related to certain things.
https://www.eccie.net/providers.php?do=view&id=646618
There's also a forum signature you can setup, which will append to the bottom of all your posts. There's rules about what is allowed to be in your signature lines, so hopefully other ladies or a mod will pipe in with the rules.