This short tutorial by user shows us how to add a user to the wheel group on FreeBSD.

Original: http://www.cyberciti.biz/faq/howto-freebsd-add-a-user-to-wheel-group/

How do I add a user to the wheel group in FreeBSD unix operating systems using command line options?

Tutorial details
Difficulty Easy (rss)
Root privileges Yes
Requirements FreeBSD+pw
Estimated completion time 2m

You need to use the pw command line utility for adding, modifying and removing users and groups on a FreeBSD operating systems. You must be root user to modify system configuration including pw command.

Add existing user called vivek to the wheel group

The syntax is:

 
pw group mod {GROUP-NAME-HERE} -m {USERNAME-HERE}
pw group mod wheel -m vivek

If the user named vivek already exists add her to the wheel group.

Add new user called sai while creating a new account

The syntax is:

 
pw user add {USERNAME-HERE} -G {GROUP-NAME-HERE}
pw user add sai -G wheel

The above command creates the sai primary group automatically, and add a user in the wheel group when her account is first created on a FreeBSD unix operating systems.

How do I verify new group membership on a FreeBSD?

The syntax is:

 
pw groupshow {GROUP-NAME-HERE}
pw groupshow wheel
pw groupshow sai
pw groupshow vivek
## Determine Group Membership Of sai and vivek Users ##
id sai
id vivek