You need this to get it done:
Action DetailsRequirements and how-to articles for Facebook's action:
Choose up to ten images to use in your slideshow.
File format: .jpeg/.jpg or png
Resolution: Minimum of 1,280 x 720 pixels
Ratio: 16:9/1:1/2:3 (should be consistent across all images, otherwise slideshow is automatically cropped to 1:1)
Choose a video to use stills from.
File format: .mov/.mp4
Either upload your own audio (if you own the rights to it) or choose from the list of available music tracks.
File format: .wav/.mp3/.m4a/.flac/.ogg
Add captions to your slideshow (a large amount of Facebook users have video audio muted whilst browsing their News Feed, so captions are very useful for helping to get your message across without relying on audio.)
A short description to accompany your slideshow (maximum of 90 characters.)
Decide on the audience you want your post to reach (gender, age, location, interests, etc.)
Duration and Budget
Choose how long you want your ad to run and what your daily budget is.
Choose currency, enter payment details and pay.