Creation of xml sitemap for websites

I´m looking creation of xml sitemap for classified ads websites. The sitemap should be automaticaly updated after what a new content on site is added. Sitemap should be for content, images and videos.

Current I have 4000-5000 categories on my websites. Maybe it would be suitable to create multiple sitemap because when there will be many ads, so limit of 50 000 urls can be reached.