How do I add name & Pass to Plugin?

I am trying to automate a search which requires a username and password. I can’t find refrence on how do this in the Docs. Is it possible? and if so Where do I enter the information?

The URL currently is in this format

<?xml version="1.0" encoding="UTF-8"?> Description Searches the web using </>. EngineUrl https:/// Identifier / Info Libgen HN Plugin Name Libgen HN OffsetPerPage 1 Operators 59 ParseLinks ResultsPerPage 10 Start 0 Version 1.0

From the Help > Plugin Development > XML & JSON Keys

LoginURL: [string] The address used to log into a website. Usage similar to "EngineUrl" . Can contain the placeholders _agentUser_ and _agent_Password_ .