Choose disk druid as the tool to be used for this purpose. Next will come a screen with all the information about your hard disk and the partitions in it. DO NOT do anything with the partitions made for windows themselves. You could end up deleting your entire hard disk. By now you would have read the disk partitioning methods in the previous articles and will have some free space outside of the windows partitions.
Choose add a partition. Now Linux needs two basic partitions - one for the root and one for the swap file, which is very important in Linux. Add a partition first for the swap file. The size of this should be approximately twice the size of your RAM. This swap file is used for virtual memory management. It does not concern you and is managed entirely by Linux itself. So quit worrying about it. Click on the add button and chose the type as Linux swap. You do not need to provide a name.
Once this is created, click on the add button to create the root Linux partition. The type is specified as Linux native and is mounted at point "/" In Linux "/" is called as the root directory. The size of this partition is the size of the remaining area free on the hard disk. There is an option called as grow to fill disk that you should choose. Then you won't have to specify the size.
Choose done and save the changes to the partition table. Remember, once you say save changes there is no comeback. Be very careful. It will then ask you whether you want to partition the hard disk. Say yes and do not check for bad sectors.
The Next part is something called as Lilo. Lilo stands for Linux Loader. It is the program that resides on your MBR (Master Boot Record) and does the booting. In only windows, we have only a single operating system. Hence there is no problem of dual booting. Lilo gives you a choice of which OS you want to boot into. The Windows partition is called as DOS and the Linux one as Linux. You can choose your wish at the boot up time. Install Lilo into the MBR and then move on to the next part.