@Alison813 I would put it at the top of the description.
PLEASE NOTE: This home-share listing is available for female guests only.
If a guy tries to book, just politely say that you're sorry, but you only accept female guests in your home-share and that that information is found in the first line of your description. If they respond in a nasty way, don't answer, just report them to Airbnb.
I would also not use IB.
Also change the title of your listing to work in "Female-Only"