How to navigate on a list

some webpage has unordered list (<ul><li>...</li></ul>). when click to select item, navigate page. how can use powershell similar following?

$ie = new-object -com internetexplorer.application 
$ie.visible = $true
$ie.navigate("http://www.awebsite.com")
start-sleep -seconds 2

....

$signout = $ie.document.getelementsbytagname('a') | where-object {$_.innertext -eq 'sign out'}
$signout.click()

just found workaround using $ie.document.getelementsbytagname('a')) | where-object, spend lot of time try & error

Windows Server  >  Windows PowerShell