Real debian is challenging to learn and requires good knowledge and...
Real debian is challenging to learn and requires good knowledge and understanding of Linux to achieve good results.
Being new to Linux, you either want sidux or Mint if you are interested in using debian Linux.
Buy an 8gb (Minimum size) Usb flash drive from you local computer vendor, plug it into your computer and install sidux or mint using a downloaded installation cd by burning the iso image to disc and booting your computer's bios from it.
If you are asking about repartitioning your hard drive :
may help you to learn how to resize partitions.