ld.so.config error / Quake 3 error

[I dont have one]

When i try to run ./configure i get the cannot load libx11 error, i have heard i have to edit ld.so.config....but whut do i do? Also when i try to run the Quake 3 demo i get the error that the libs cannot open from /etc/ld.so.config Can someone help please? Thanx