try to download RHEL v6
 

how to download an iso of RHEL 6.3?

RedHat products page: RedHat Products
RedHat download page: RedHat Downloads

- You do need an account to access the actual download url's.
- RedHat products are _not_ free, you need a paid subscription to use it.

Server based alternatives for RedHat EL (free and 99.9% compatible):
- CentOS
- Scientific Linux

Consumer based alternative for RedHat EL (free, and geared toward home usage):
- Fedora