Lets assume you have chosen the value "adspirit2019" for your retargeting pixels and are now tagging visitors with this pixel.
Now go to the targeting section in the campaign or on the creative and enable Re-Targeting ...
... and insert the value into the field ...
That's it. The campaign will now only be delivered to users that are tagged with this value.
Separators for retargeting pixels in campaigns/creative
The semicolon is used for connecting two values with logical AND. The campaign will only be delivered if the user is tagged with both values.
The pipe is used for connecting two values with logical OR. The campaign will only be delivered if the user was tagged with at least one (or all) of the values.
Exclamation mark (!)
The exclamation mark can be used to determine that a user must NOT be tagged with this value. The exclamation mark therefore is no seperator but an addition to an existing value. The exclamation mark must always stand behind the value.
Min./Max cookie age (Days)
These settings specify how old/new the your retargeting cookie may be in minimum and maximum. In other words it specifies when the user was tagged the last time.