Hi,
someone can tell me where i can find the Icann tech documentation that we can use to development the software to register domains with Icann?

There is no such thing, you're actually dealing with the registries not ICANN.
There are EPP kits out there, and also RFC documentation.
Take a look out for NET.DRI, http://www.dotandco.com/services/software/Net-DRI/, thats a good chunk of the connection calls made for you.

Yes, Net:DRI is one of the best solutions when you want to use Perl. The package also includes the RFC's.
When you want more specific documentation go to the registry websites, e.g. http://info.info/faq/11

If you're contemplating a high-speed, high-availability solution, I'd suggest using a compiled language like C. You won't have the interpreter's overhead and you'll have much better control of the environment.
There are registry-specific EPP kits in Java that you can get from the registries if you want to go the Java route. Some provide C source examples, too. Note, however, that their example code is not a complete working registrar system. They merely show how to interact with that specific registry, nothing more. Each registry -- even those using the EPP "standard" -- is different. Some have back ends that are quite arcane.
And there are lots of details. On the registry side, the ICANN side, and your own business' side, too.
Learn as much as you can before you start creating. The devil, as they say, is in the details.

If you're contemplating a high-speed, high-availability solution, I'd suggest using a compiled language like C. You won't have the interpreter's overhead and you'll have much better control of the environment.
The only reason to use C may be the speed. You can also compile Java or let Perl run as a service.
High-availability is important, but has much more with your server setup and OS to do than with the programming language you choose.
For the control of the environment it doesn't matter if the language is interpreted or compiled.
Each registry -- even those using the EPP "standard" -- is different. Some have back ends that are quite arcane.
That's a valid point and will use some time. Most registries are quite conform, the biggest problems are with the ccTLD (e.g. Nominet only kept the name EPP of the specification and not much more). Neulevel also made some different implementations, but they are standard confirm as the standard itself isn't always that detailed.
Learn as much as you can before you start creating. The devil, as they say, is in the details.
And plan much time for the certification tests with the registry. They are the biggest pains as you have to prove stupid things like that when you register an invalid name you see the right return code. Quite often I thought it's more certifying the registries system then yours.

The only reason to use C may be the speed. You can also compile Java or let Perl run as a service. High-availability is important, but has much more with your server setup and OS to do than with the programming language you choose.
For the control of the environment it doesn't matter if the language is interpreted or compiled.
In our particular case, we decided that efficiency and speed were two very important qualities. Combined, they increase the availability of the system; instead of wasting clock cycles (by not using them as efficiently as possible) we can process more transactions per unit of time. And while the nature of the language may not matter to some, a compiled language is our preference.
Please understand that this isn't meant as an attack; I don't want to get into a religious debate. It's merely how we chose to approach this non-trivial problem. :)

ok thnaks for all, last question, is there any ready solution software that we can buy to start with Icann?

Please understand that this isn't meant as an attack; I don't want to get into a religious debate. It's merely how we chose to approach this non-trivial problem. :)
No problem, mine was also not meant as attack, just an other point of view.
As for every problem there unfortunately many solutions and you have to pick one at the end.
ok thnaks for all, last question, is there any ready solution software that we can buy to start with Icann?
Have a look in the signature of Domainitor, there is LogicBoxes, but that's a hosted solution. Think you can also buy openSRS's system, not sure if that's a hosted solution or not.
You get the most flexibility by developing it yourself. That way you also can offer services and solutions other can't.
If you find a software you can buy as base and then modify it would reduce your time-to-market.