How did the Balkan Wars lead to the assassination of Archduke Franz Ferdinand?

I assume that you are talking about the Balkan Wars of the
early 1910s and the assassination of Archduke Franz Ferdinand.  If so, the Balkan War
led to the assassination because they inflamed Slavic nationalism and hatred of
Austria-Hungary.

The Balkan Wars mattered because Serbia
was using these wars to take more territory, in particular a port on the Adriatic Sea
(access to the ocean is very important for economic and military reasons).  Austria did
not want Serbia to get these territories.  After the wars, Austria (with help from other
European nations) forced Serbia to give up the territories it had gained.  These actions
made Serbia (and the Slavs in the region who identified with Serbia because it was a
Slavic country) very angry at Austria.  This anger led to the killing of the Austrian
Archduke.