Which file to download binary, rpms or srpms?

Hello:

I just want to download a binary latest postgres completely to install on my
redhat. When I browse the web, I have to browse deeply into the
directories.

http://www.postgresql.org/ftp/binary/v8.2.4/linux/

Then

I have no idea the difference of rpms and srpms.

So many packages under

http://www.postgresql.org/ftp/binary/v8.2.4/linux/rpms/redhat/rhel-es-5/

Even after I downloaded it, how can i install it?

.

I have no idea why they put so many time to develop the software while so
mean to write more document. Only a couple of line is good enough!

Thanks.

Have a nice day.

Z. Du