You can only connect thru ultrapeers. If you turn on the connections window & have a look, all those connections you see are Ultrapeers. LW Basic connects thru 3 ultrapeers, LW Pro connects thru 5 UP's which allows a slightly improved search for the rarer to find files.

If however you are running as a T3 connection you can connect to more.

But as the topic of the thread suggests, you are wishing to host, which means sharing files. You can do that in a few ways. One is via partial file sharing, another is sharing finished downloads, another is via adding your own share folders.
eg: some iTunes music folders. How to Share Folders (click on link)