More detail about just what you're trying to do would be helpful, but based on what you posted
on *:text:!add:#:{
  set $+(%,nicks,.,$network,.,$chan) $addtok($+(%,nicks,.,$network,.,$chan),$nick,32)

When a person types !add it will add their nick to the list for that channel. If the same person types !add more than once, it won't matter as the list will only contain each nick once.