Compare 2 header of a csv file

I have 2 csv files as like below
First.csv
Header1,Header2
abc,xyz

2nd.csv
Header1
abc

The output I expect is as below
Header1,Header2, Header3
abc,xyz,Comment

I am trying to use the below script but not just able to put it in place.

$CSV1 = C:\Path\To\File1.csv
$CSV2 = C:\Path\To\File2.csv
$CSV1|ForEach{$|Add-Member ‘Name ID’ $Null}
ForEach($Record in $CSV1){
$Record.‘Name ID’ = $CSV2|Where{$
.ID -eq $Record.ID}|Select -Expand ‘Name ID’
}

I’d love to help, but your post doesn’t really make sense.

Is Header3 meant to include a comment saying “Header 1 value Exists in both spreadsheets” or something along those lines?

Header3 can contain any custom comment say “ok The value is available”

You probably want something like Join-Object: http://blogs.msdn.com/b/powershell/archive/2012/07/13/join-object.aspx