The syntax for adding a user account via the net (according to the man page) is shown here:

net [<method>] user ADD <name> [-c container] [-F user flags] \
    [misc. options] [targets]

The user account password may be set using this syntax:

net rpc password <username> [<password>] -Uadmin_username%admin_pass

The following demonstrates the addition of an account to the server FRODO:

root#  net rpc user add jacko -S FRODO -Uroot%not24get
Added user jacko

The account password can be set with the following methods (all show the same operation):

root#  net rpc password jacko f4sth0rse -S FRODO -Uroot%not24get
root#  net rpc user password jacko f4sth0rse \
    -S FRODO -Uroot%not24get