"Community" connections???

[jpdude]

I'm a fairly new user, so please forgive my ignorance. Does the community that you connect to affect the search results, or when you key in a search does it look thru the entire network? When i use the connect button in the lower left corner (next to the red/green light), i can most always connect...but if i hightlight a particular community and use the other connect button (next to the logout button), i am very rarely able to connect...it usually disconnects me from the network! Am i doing something wrong? Which connect button is the right one to use, or does it matter? I noticed where it says to connect to the appropriate network group for optimal performance, but that never seems to be an option for me because it always disconnects when i try that......any insight would be greatly appreciated!!! Thanks for listening!!!! :-)