how to add user to the doman admins group through powershell code example

Example 1: popwershell add local user

$Password = Read-Host -AsSecureString
New-LocalUser "User03" -Password $Password -FullName "Third User" -Description "Description of this account."

Example 2: how to add a group windows powershell

New-LocalGroup
   [-Description <String>]
   [-Name] <String>
   [-WhatIf]
   [-Confirm]
   [<CommonParameters>]