Trying to make WP into a classified ad site.

Hi I want my readers to be able to place an ad and photos onto my WP site. I will put them into the site as a post, under their catagory.

Is there a plug in or how can I make a form that the reader can write their details of their ad, upload a photo and hit a submit button.

Its important that they can upload their photo.

Thanks for any help.