this would make "sandra" of the group "geeks" the owner of all of the files and directories inside "/example":
chown -R sandra.geeks /example/*
this would make "sandra" of the group "geeks" the owner of "/example", as well as all of the files and directories inside it:
chown -R sandra.geeks /example
http://www.die.net/doc/linux/man/man1/chown.1.html