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

paid action
Create an image ad to appear in users' News Feeds.

You need this to get it done:

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.)
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.)
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.
Facebook Photo Ads
Information about photo/image ads - when and how to use them.
Link missing here or found errors? Improve How-Tos