I have on may PC qt3, qt4.5.1 and qt4.5.3 is on the way, most important there is no problem at all to have all versions.

so as yogeshgokul suggested - first download the latest version.
untar it, go to the qt directory and run
./configure --help
that command will give you more answers on where and what to build.
when the configuration is done... run make and as root run make install

and here it is, a new version.

PS: you have in qt directory a file INSTALL and README and is a good thing you read it