Automatic form poster on website

We would like to have a tool developed to automatically post ad's to a dutch website. Basically the tool should do as following: Login to the website. Create a ad. Choose one main category and the choose a subcategorie. Post the form -- a new form will be opened. Fill out all advertisement details, like price, description, title, Upload 2 or 3 pictures and some other details should be filled out automatically. Then post the ad. I'd like to have some kind of database or csv file where all content will be stored. I'd like to have a scheduler, so the postings will be done on some specific times + some kind of delay (like 15 minutes) so the script won't post all ads to quickly. I prefer to have it written in PHP, so it can be run from a browser. But if this would be promlematic a desktop version would also be ok, as long as it can be run in the background.