This is a useful site http://www.lamolabs.org/blog/164/centos-rpm-tutorial-1/

1 prepare environment

yum install rpm-build
mkdir -p ~/rpm/{BUILD,RPMS,SOURCES,SPECS,SRPMS,tmp}

Create a branding file 

vim ~/.rpmmacros
 
### contents of the file ###
%packager Vic
%_topdir /home/vic/rpm
%_tmppath /home/vic/rpm/tmp