Getting a list of items from document library using PowerShell

Question

So if I have the URL for a Document Library, how can I get all the items (in this case, folders) from inside the library? I've tried a few different things, but I can't seem to get it.

This is what I've tried so far:

$web = Get-SPWeb($completeUrl)
$spDocumentLibrary = $completeUrl + "/DocumentLibrary"
$spSite = Get-SPSite -Identity http://url.com
$website = $spSite.OpenWeb()
$listItem = $website.GetListItem($completeUrl)

And it fails with an Exception calling "GetListItem" with "1" argument(s)...

I'm not reeaally sure where to go from here. What I'm interested in is getting all the folders I have in the document library, which I know is found at $completeUrl + /DocumentLibrary which would equal something like http://url.com/../../DocumentLibrary for example. But I'm apparently going at it wrong.

Any hints?

UPDATE 1:

So with a little inspiration from John below, I've modified my script:

$web = Get-SPWeb($completeUrl)
$spDocumentLibrary = $completeUrl + "/DocumentLibrary"
$site = New-Object Microsoft.SharePoint.SPSite($spDocumentLibrary)
$website = $site.OpenWeb()
$list = $website.GetList($spDocumentLibray)

This gets me the wanted document library, now I'm going for all the items inside it.

UPDATE 2:

    foreach($item in $list) {
        write-host "listItem: " $item.Title
    }

This just gets me the same as $list. Any ideas to what I'm doing wrong?

UPDATE 3:

It seems I also had to include the following to be able to do the foreach above:

$items = $list.GetItems()

Answer 1

I haven't tested this but should be something like that I think,

$web = Get-SPWeb($completeUrl)

$spDocumentLibrary  = $completeUrl + "/DocumentLibrary"  
//do you also need to put a /lists before the list name I wonder(if it's a list)

$list = $web.GetList($spDocumentLibrary)
$items = $list.GetItems()

foreach ($item in $items)
{
//do whatever you need to do
}

Answer 2

GetListItem() only gets you one specific item from the list and your URL points to the list only, not to an item.

Try first to use GetList() to get the List object, then you should be able to walk through the list or do a Query on the items in the list.