SQL Server 2008 Powershell

Hi experts I would like to ask help on writing Powershell script for below.

First I would like to Select the Database.                                                                                                                           Second Create a Temp Table                                                                                                                                        Third I would like to Get the Two tables like this @DBName+'.dbo.sp_helpuser'                                                 Fourth Then insert the data in the Temperary table

set @ dbname =Select   name from master.dbo.sysdatabases
                where Name not in ('tempdb','Pubs','Northwind','Model')
 
            -- get DB info
 
                If (Select isnull(object_id('tempdb..#DBUser'), 0)) = 0
                    Create table #DBUser_08 (
                    UserName varchar(150) null,
                    RoleName Varchar(1000) null,
                    LoginName Varchar(200) null,
                    DefDB Varchar(1000) null,
                    DefSchemaName varchar(500) null,
                    UserID int null,
                    SUserID int null
                        )
                Truncate table #DBUser
                       
                Declare @DBQuery varchar(200)
               
                Set @DBQuery = @DBName+'.dbo.sp_helpuser'

                  Insert into #DBUser exec (@DBQuery)