Creating an Ad set

Draft campaign

Add an audience to your campaign by clicking New ad set in the middle of the screen in the campaign wizard. 

Once you've clicked the New ad set option, you need to choose your audience types. You can add as many audiences of any types to a single campaign as you wish to.

Once you've selected an audience type, you can specify your options by clicking on Grouping, Placement, Bid info, Filters or Advanced.

Running campaign

Have you forgotten to add an ad set to your campaign, but the campaign is already running? If that's the case, that won't be an issue. 

To add a new ad set to a running campaign, open the campaign, then go to Performance Insights, and finally click on New ad set

And, that's it! You can now add your ad sets and audiences as usual.