You created a Facebook pixel but when you go to create your ad you don’t see the pixel or any pixel?

Assign the pixel to certain ad accounts so that it can be used in your ad campaigns

https://www.facebook.com/business/help/314143995668266?id=1205376682832142

Create a pixel in Business Manager

1. Go to Business Settingsin Business Manager.
2. Select your business.
3. Click Data Sources.
4. Select Pixels.
5. Click the + Add
6. Type in a name for your pixel.
7. Optional: Enter your website URL.
8. Click Continue.
9. To install your pixel on your website, click Set up the Pixel Now.

ADD created pixel to ad account

Go to Business Settings in Business Manager.

1. Select your business.
2. Click Data Sources.
3. Select Pixels.
4. Pick pixel to link & click
5. Optional: Click Connected Assets
6. Click Add Assets
7. Select Asset type column > Ad Accounts
8. Select Assets column > add your Ad Account