In order to release a device to the market, You need to run the Compatibility Test Suite given by android...I need to know how to download and run it..
If you're working to release a new Android device, then surely you're already in contact with Android?
They only provide the Android Compatibility Definition and Test Suite docs to those people they're working with to bring a device to market.
As XC said in a comment, as of 2.0, the CTS is freely available.
For it to be runnable, you have to build the tests. In your top level android directory, do all the normal build set-up steps and then
make cts
Then in the out/host/linux-x86/cts/android-cts/tools
sub directory, you will find the startcts
bash script. I expect the location might depend on what platform you are building on. Modify it to point out your SDK and then run the script. It is relatively self explanatory.
There is a quite good documentation on Android's source website. Also, some time ago I've wrote small crash course on CTS: http://bitbar.com/blog/44/using-androids-compatibility-test-suite .