#1 - July 28, 2014, 5:30 p.m.
Once the zone is open, Nexus-Lord Donjon Rade (in Stormwind, Orgrimmar, Shattrath, Dalaran, Vale Shrines, or your garrison) will have a chat option to teleport you into the Foundry. Assemble your group, set the raid difficulty to Heroic, and then use that option to enter. Head to your right, and then take a left as you enter the Slagworks T-intersection, to find Oregorger. (He's opposite the hallway that leads to Gruul, if you did that test also.)
In your posts, please note your group size and makeup (high-end guild group, PUG, multi-guild team, etc.). Uploading and linking to a log parse at Warcraft Logs, or any similar site that can handle 6.0 logs, would also be quite helpful.