For people wanting to download media files on? And are all Linux os’s free or atleast the good ones? Is there any point of me putting linux on my d drive so I can switch back and fourth from windows 7 to Linux?

I have a PC with C: and D: drive. Old OS is Window ME. I plan to clean format them and install Linux OS. How could I do it? In particular, how can I format the C: and D: drive.