Scroll down to see how to do this in Symphony 1.5
In Symphony 2.0:
Find a room to join in advanced search under the Chats section. From the search results, join a public chat room or request access if the chat room is private (figure 1).
Figure 1 Search for a room to join or request access to
Note: Some rooms are hidden from search and do not appear in results. To join the room, you must be added by a member of the room.
In Symphony 1.5:
Search for a room to join using the Search bar (figure 1):
Figure 1 Search Bar
Click to join a public chat room or click Request Access if the chat room is private (marked by a lock icon).
Note: Some rooms are hidden from search