The version of git that comes with RHEL6 is very old. I'll outline steps for compiling the latest git version on RHEL6. Working from /usr/local/src.
Following instructions for Git Pro book Getting Started Installing Git.
yum install gcc curl-devel expat-devel gettext-devel openssl-devel zlib-devel perl-ExtUtils-MakeMaker
Optional man page prereqs.