the following page will appear with software version displaying on its left shown in yellow shade.
To download 9.1 or below version click archive at the bottom, otherwise click the version shown.
For example if you want to download Xilinx 10.1 version select 10.1
it will display list 10.1 version software. ise,edk,chipscope,dsp tool,planahead, also it will display complete package of entire software.
If you click Xilinx ISE it will take you to login page.(Also in the same page you have option to obtain license. click that will show you serial key of the software copy that key to wordpad). register your name to login.
After login it appear download file.once you click download file it starts downloading.
Tips: Use download manager software for faster download.
Now install the downloaded software. paste the serial key when it ask.
Now you got your free version.