Configure the addon under standard Interface AddOns options, or via /nl opt.
Loot masters can either start a session with items from their inventory, or request to view bids in an existing session.
Loot masters in the raid can see which raiders are interested in which items, and assign them accordingly.
Raid members can view items added to the loot session by a loot master, and select BIS, Upgrade, OS, or Pass. There can be multiple sessions active at a time.