To add a user to a group in FreeBSD, you can use the pw command with the usermod option. For example, to add the user john to the group wheel, you can use the following command:
pw usermod john -G wheel
This will add the user john to the group wheel.
Alternatively, you can use the usermod command with the -aG option to add a user to a group. For example:
usermod -aG wheel john
This will also add the user john to the group wheel.
It's important to note that you may need to be logged in as the root user or have superuser privileges in order to add a user to a group.
You can verify that the user has been added to the group by using the id command:
id john
This will print out information about the user, including the groups that they belong to.