What should I change so that when adding a user there is a choice of groups to which to add it?

Question

CodeIgniter

When adding a user, the message "the group is set incorrectly" is displayed, despite the fact that editing the user is carried out in principle tolerably, as a result, by analogy, I tried to "conjure" in the file to create the user (using the editing example) as a result I got a bunch of errors with a link to the controller, muddling I realized with the controller that I can’t handle it myself, so I decided to turn here. fortunately, before my execution, I thought of making a backup copy ... I
posted the links below to the file for creating a user, editing and to the controller itself. (The volume of the text did not pass).
Actually this is codeigniter
Help pliz solve this problem, below I attach a copy of the file code for creating users and the controller itself. Thanks in advance, please don't kick me, I'm not a programmer (our programmer escaped, but I'm generally an advertiser) :(
the controller
itself adding a user
editing a user
Posted on codepen :
codepen.io/codermen/post/polechudes
PS> Thanks in advance!