If you want SSL on apache for secure transactions to your website you need to install open ssl and mod ssl. If you are running redhat 7.x openssl should be installed by default in rpm format as it is needed by openssh. If you don't need SSL support skip this guide and go directly to the basic apache installation from source code.

files needed:
open ssl - http://http://www.openssl.org
mod ssl - http://www.modssl.org
shared memory manager - http://www.engelschall.com/sw/mm
apache source code - http://apache.org/dist/httpd

get the source code -
Create a directory to work from and download the above into that directory then untar the archives:
# tar -zxvf filename.tar.gz
This will decompress the files in question and create direcories containing the source code for the respective archives.

verify that you have openssl installed
# rpm -qa | grep openssl
This will return with a listing of "openssl-xxx" and "openssl-devel-xxx". If so, go to the next step. If not download the source code from the above link. 
Check out the README file
# less README
I t will tell you that the instructions for installation are in the INSTALL file
# less INSTALL
Follow the directions.

patch the apache source code with mod ssl and the shared memory manager 
# cd mod_ssl-2.x.x-x.x.xx
# ./configure --with-apache=../apache_1.3.xx --with-mm=../mm-1.xx

What you have just done is patch the apache source code to include mod ssl and utilize the shared memory manager. After Apache is installed you can install a ssl certificate and enable the ssl features you just compiled into apache. For instructions on how to do this, I would contact a certificate authority like verisign or thawte as you can purchase a ssl cerificate from them and get instructions on how to install it. Otherwise to install a bogus certificate for testing purposes, check out the documentation in the mod ssl and apache directories. Additionally, I would read the README and INSTALL files in the mod ssl directory.

now build your basic apache installation