How to install git to red hat enterprise linux 5.3 x64?

Use the EPEL (Extra Packages for Enterprise Linux) repository. The easiest way to enable it is by installing the epel-release package. Here's how if you have RHEL 5 x86_64:

[root@localhost]# rpm -Uvh https://dl.fedoraproject.org/pub/epel/epel-release-latest-5.noarch.rpm
[root@localhost]# yum install git

For a more up-to-date version of Git (1.7.2.3 at the time of this writing versus 1.5.5.6 in the EPEL repository), see Andrew Thompson's Webtatic repository:

http://www.webtatic.com/blog/2009/09/git-on-centos-5/