Need help with powershell script to add information to a CSV file

Hi 

I have a powershell script that used to create an html file but is now being converted to a csv file.

Most of it is working. There is a part in the script where it finds the last logon for the user to be 0 or greater than 30 days and it used to highlight these users in red in the html file.

I am trying to work out a way to do a similar thing in the csv file. I realise you can't change colours in the csv file but I wanted to see if an extra column with say yes could be added next to the users who have a logon of 0 or greater than 30 days.

Below is the script

Import-Module ActiveDirectory
. .\ConvertTo-DN.ps1
$UserOUDN = ConvertFrom-Canonical -canoincal "contoso.local/MyBusiness/Users/SBSUsers"
# Format the number column
$count = 0
$rownum = @{label="Num";e={[int]}}
# Get the list of users
$users = Get-ADUser -filter * -searchbase $UserOUDN -Properties SAMAccountName, GivenName, Surname, EmailAddress, Description, LastLogonDate, Enabled | Select-Object $rownum, @{e={$_.SAMAccountName};n="Username"}, @{e={$_.GivenName};n="First Name"}, @{e={$_.Surname};n="Last Name"}, @{e={$_.EmailAddress};n="Email"}, @{e={$_.Description};n="Description"}, @{e={$_.LastLogonDate.tostring("dd/MM/yyyy")};n="Last Logon"}, @{e={$_.Enabled};n="Enabled"} | Sort-Object "Last Name" 
# Increment the number column and append to table
foreach ($user in $users) { $user.Num = $count += 1 } 
$UserCount = $users.count

if ($user.'Last Logon' -eq $null) {
        write-host "yes"
    } else {
        $now = Get-Date
        $LogonTime = [datetime]::ParseExact($user.'Last Logon',"dd/MM/yyyy",$null)
            
            
        $span = $now - $LogonTime
                
        if ($span.days -gt 30) {
            write-host "yes"
        }
        
        
    }


$users | Export-Csv -Path tt.csv -NoTypeInformation

Any help appreciated

Jimi005