Switch Packs comes in many combinations from one switch to boxes with multiple switches.
Common is that they only have an on and an off value.

There are many approaches to a fixture for switch packs.
Single channel generic fixture with one on and off button.
If this has to be used with a multiple switch pack then the same fixture has to be placed multiple times on adjacent addresses in FreeStyler.
Here it is necessary to add the number of fixtures that fits the switch pack to occupy the addresses.
Multiple channel generic fixture.
All switches are in one fixture but if they are used for different purpose it can be a bit difficult to remember what they are used for.
User defined fixture.
Is the same as above but just with a picture of the fixture that they actually are used to control.

In this example a “user defined” fixture with a 4 channel switch pack will be shown.

Before starting to make the fixture there are some thing that are to be prepared.
Find a Fixture picture.

See Link Fixture Creator - Before making a fixture.
See Link Fixture Creator - Pictures and Icons