SharePoint 2010 : Update the value of a column in library

update-column.ps1

cls
if((Get-PSSnapin | Where {$_.Name -eq "Microsoft.SharePoint.PowerShell"}) -eq $null) {
    Add-PSSnapin Microsoft.SharePoint.PowerShell;
}

$sourceWebURL = "http://sp2010/sites/"
$sourceListName = "Library Name"

$spSourceWeb = Get-SPWeb $sourceWebURL
$spSourceList = $spSourceWeb.Lists[$sourceListName]
$spSourceItems = $spSourceList.Items | where {$_['Title'] -like "*Lorem*"}
$exdate = '{0:M/dd/yyyy hh:mm:ss tt}' -f (Get-Date)

$spSourceItems | ForEach-Object {
	$_['Created'] = $exdate
	$_.update()
}

Line 6 : Write the URL of your site.
Line 7 : Write the name of your Library
Line 11 : Write the condition for your script.
Line 15 : Name of the columns you want to update.