Welcome to ATP, Marcia, and thanks for your kind offer.
Several times I've been surprised by how few people here are looking for seeds. Some people have been gardening so long that they've filled all their available space,a nd have to give up one plant in order to start another!
If you go to the link that Danita posted, you can click on the big dark blue button that will add that plant to your list of plants. Far right, and you might have to scroll down a a little to see it. (I forget if it will create your list from scratch if it's your first plant.)
Then you can mark it "available for trade". I think you would have to create a private "Category" for "available for SASE" if you want interested people to know about your kind offer.
@SCButtercup might be interested.