Find the currently empty users section inside your permissions.cfg:

users {
}


For each user add in the following inside the existing user brackets above:

KenMerritt {
groups {
- 'admin'
}
}


The completed section would look like this:

users {
KenMerritt {
groups {
- 'admin'
}
}
}


Just in case you are still confused here is my entire Permissions.cfg file containing two admins:

guest { # Unregistered users will use these permissions.
nameFormat = '%name%'
chatFormat = '%name% : %message%'
guildFormat = '[00CC00][%guild%] %chatFormat%[-]'
}
groups {
default {
default = 'True'
permissions {
- 'rok.chat.me'
- 'rok.chat.guild'
- 'rok.health.suicide'
- 'rok.help.list'
}
}
admin {
permissions {
- '*'
}
}
}
users {
KenMerritt {
groups {
- 'admin'
}
}
jamhorne {
groups {
- 'admin'
}
}
}