How can you add a new user
There needs to be a lot more information with your Question.
Are you wanting to add a user to Laserfiche, to forms, or to both?
Do you have Avante, Rio, or Team/United licensing?
Do you want to create a Windows AD user or a Laserfiche user?
Have you checked if you have an available license to add a user?
Does your user have permissions to "Manage Trustee" (or administrator)?
For some background, this documentation covers these processes in the repository.
Without addressing any of the very important questions raised by Bert, you add a new user to Laserfiche with the Laserfiche Administration Console.