I'm try to download Evaluation Red Hat Enterprise Linux Desktop 6 from Red Hat but It shows
Please help me!

Welcome to LQ
Perhaps you can do what it says:
Kind regards

Do you have direct link?
Thanks!

I contacted Red Hat but they don't rely me. What can I do?

Keep trying... otherwise CentOS? Scientific Linux?

spend the cash and buy it
it is not 100% free

https://www.redhat.com/wapps/store/catalog.html

Red Hat Enterprise Server has a 30 Day evaluation available upon registration.
If you start the download, but cancel it - you get the message that the questioner posted.
If you take longer than 30 days to download - you get the message that the questioner posted.

We took too long in between downloading an evaluation copy and installing it on our new server.
So, we have received the same message.

Since we were going to purchase RHES for 8 servers anyway, it is not about money.

There are legitimate reasons to need an evaluation copy from a manufacturer.
It is not always being cheap like many of the comments indicated.

As your server requirements get more complex, as you wait on custom configuration of proprietary programs for your site, as you wait on parts being back ordered, or as you wait on chip delays from a manufacturer; you realize that a 30 day time period to evaluate is way too short for most companies or institutions. A 90 day period would be more reasonable.

For IBM Power, I think there is a 60 day evaluation period for RH and for SUSE.
VMWare is 60 days on a lot of packages also.

Out of curiosity, did you contact Red Hat, explain the situation, and ask for an extension of your 30 days? What was their response?

We had someone from RH contacting us for 3 months, every few weeks.

When I said that our evaluation seems to be expired prior to download, the response was "I will see if I can get an extension for you". They also asked us more questions regarding our installation, when we were going to start, equipment, rollout, 12 month plans, support, response times, etc. Basically, it seems they would extend an evaluation with enough justification. No deception on their part, just a 30 day limited window.

As we need this server up 2 weeks from now to meet our deadline, we are going to go ahead and purchase the software.
We know enough about RHEL 6, the hardware is all certified, the other programs are all certified, no real reason for us to go the evaluation route. It would be nice to use the eval from 11/01/12 to 12/31/12 and have the registered version and support start 0101/13. But that make RH revolve around our sun, not their view that the rest of the universe revolves around them.