Provided you have a fairly modern pc with no operating system installed on it, how do you create a software from it? I can't find anything that explains this but I guess you can't? As It's practically impossible to write to hard disk using your hands. But you can create a program from computer that uses punch cards? Thank you in advance for explaining this topic to me.
It's not practically impossible to write to an HDD using your hands, it's actually impossible.
If you only have that single computer and no means to build any devices that will be compatible with it, then there's no way to do it.
You could conceivably build a USB punch card reader that look to a computer like a (really slow) mass storage device. You would also need to design x86 punch cards, since none have ever existed, to my knowledge. Then you can hand write the bootloader and boot a hex editor so that you can write to the HDD, and from there you can code by just directly modifying the contents of the HDD.
That's not really true. You can turn on a PC without an OS and it will display something on the screen, just not anything particularly useful.
BIOSes could include hex editors to modify the content of mass storage devices. Then you could do something useful with it even without an OS. It's just that there are very few instances where it could be useful.