This is the incomplete looking for raid interface from early in the PTR. As you can see, all of the raids are bunched up by expansion. Also, the interface was not usable at this point.
When you're not in a raid, the raid window itself will link you to the actual Looking for Raid interface listed here as the "Raid Browser"
At level 80, this is what you should see when bringing up the raid browser itself. Raids are sperated out by expansion and 10 vs 25 man. So, if your guild is a 10-man raiding guild and you pug 25-man, then just uncheck the 10-man section and away you go.
Here you can set if you want to queue for lower tier raids from vanilla WoW or Burning Crusade. While these are available for selection currently on the PTR, there is no guarantee that this will be the case when it hits the live realms.
Just testing out the message feature.
When you list your name using the button at the bottom, it greys out the sections for you to change. Currently, it does not disable the message window at the bottom, but that might be a bug. If you wish to remove yourself from the queue, just unlist your name with the button at the bottom of the window.
When you first select the browse tab at the bottom, the window will be blank. There is a dropdown in the upper-right corner that allows you to choose which raid pools you wish to recruit from.
As you can see, I'm browsing the Naxxramas (25 player) pool of people. We've got me queued as a tank and a rogue and a hunter both queued as dps. Since I can't really recruit myself, I'm greyed out in the interface.
This is just testing the tooltips in the interface. As you can see, my comment from the other page isn't showing up in the tooltips. This is probably a bug and will likely be fixed in an upcoming PTR build.
Here's a look at the dropdown for the window. Nothing major, but each raid is under each normal heading like over on the main page of the Raid Browser
This is my level 63 druid. As you can see, he only has the level 60 raids available to him currently. I don't even have the option to view the Burning Crusade or Wrath raids in the list.
Like Trade, the LFG channel is now enabled in all major cities. This means that by default, you can pester people about groups on the actual LFG channel and don't have to do it via Trade or General. It is also unbound from the LFG interface meaning that there is no excuse not to use it. So, please, stop spamming Trade channel with group info.