In Facebook Ads Manager, you have created an Ad Campaign and built an Ad Set of your target audience, so now you need to build an Ad.
1. Give your ad a name
2. Identify the Facebook Page and/or Instagram account you want it connected to
3. Create your ad
4. Choose your format e.g. single image, video, carousel etc
5. Select your image, video or create a slideshow
6. Add your copy for primary text, headline, description and a URL or call-to-action button if appropriate.
Once set up, you can see a preview of what your ad will actually look like in different placements eg. mobile news feed, desktop news feed, desktop right column etc.
Either save to drafts or click the green 'Publish' button to wait for Facebook to review your ad.
Remember, it's really important to select the right visuals and words to represent your business and to attract new customers.
For more tips see: How to choose the right objective for your Facebook advertising