Action Details
Requirements and how-to articles for Facebook's action:

You need this to get it done:

Image Specs
Ratio: 9:16 to 16:9
File format: .jpg/.jpeg or .png (animated GIFs are counted as videos rather than images)
Size/aspect ratio differs based on whether it's on desktop or mobile and also whether it has a link or if it's just an image.
The link you wish to include in your post (where you would like to send your audience to.)
A short headline to grab the audience's attention and briefly explain what your ad is about (maximum of 25 characters.)
A short description to accompany your image (maximum of 90 characters.)
Post Button (Optional)
Decide whether you want to add a call-to-action button to your post (e.g. Sign Up, Shop Now, Learn More, etc.)
Target Audience
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.
Requirements missing or found errors? Report

How-To Articles
A list of useful links for you:

Facebook Ads Guide - Image (Facebook feed)
Specifications and requirements.
Link missing here or found errors? Improve How-Tos