Enabling uClinux to run on Altera DE2-115?
After you drop the components into QSYS, click the little dots in the 'Connections' column to wire them together. The grey outlines will go black once the connections are made and the errors will be cleared.

You will be greatly aided by completing the Qsys tutorials available at Altera.com, support section, search for OQSYS1000.